Help Me To Understand How To Do This Problem Plz.

Question

anonymous · Answer

attachment

mathstudent55 · Answer

We don't know how many parrotfish or angel fish he bought.
We can use the variable x to help us.
He bought x number of angel fish

mathstudent55 · Answer

He bough 6 times as many parrotfish as anglefish.
Since we let x equal the number of anglefish, how many parrotfish did he buy (in terms of x)?

anonymous · Answer

i think he bought 70 parrotfish? Not really sure

mathstudent55 · Answer

I thought you asked for help in understanding how to solve the problem.
If you want to do it your way, go ahead.

anonymous · Answer

Im sorry, i thought i was doing it your way

anonymous · Answer

sorry, please help me...i really dont understand this

mathstudent55 · Answer

It's ok. Let me explain myself more clearly.
I am guiding you toward the correct answer and also the method of solving the problem.
We need an equation that is a mathematical representation of the word problem.

mathstudent55 · Answer

We know this:
number of parrotfish + number of angelfish = 420

mathstudent55 · Answer

We also know this:
number of parrotfish = 6 times the number of angel fish

mathstudent55 · Answer

ok so far?

anonymous · Answer

yes

mathstudent55 · Answer

We need to translate that word problem info into an algebra equation that we can solve.

mathstudent55 · Answer

In algebra, we let variables (usually letters) stand in for unknown numbers.

mathstudent55 · Answer

We have two unknown numbers, the number of parrotfish and the number of angelfish.

mathstudent55 · Answer

Let the variable x represent the number of angel fish.

anonymous · Answer

can y stand for the number of parrotfish?

mathstudent55 · Answer

Since there are 6 times as many parrotfish as angel fish, the number of parrotfish is 6 times x.
How do you write 6 times x in math?

anonymous · Answer

6x

mathstudent55 · Answer

You can use y if you are trying to write a system of equations.
Are you learning systems of equations?

mathstudent55 · Answer

Good.
We have this far:
x = number of angelfish
6x = number of parrtofish

mathstudent55 · Answer

Now look at what we wrote above.
I'll copy it below so you don't need to look for it.
number of parrotfish + number of angelfish = 420

mathstudent55 · Answer

Since the number of parrotfish is 6x, and the number of angelfish is x, we replace those words in the equation with 6x and x.
6x + x = 420
Do you understand?

anonymous · Answer

yes i do, sorry i was doing something

mathstudent55 · Answer

Here the equations are color coded to make them clearer.

$\color{red}{number~of~parrotfish} + \color{green}{number~of~angelfish} = 420$

$\color{red}{number~of~parrotfish = 6x}$

$\color{green}{number~of~angelfish = x}$

$\color{red}{6x} + \color{green}{x} = 420$

anonymous · Answer

okay

mathstudent55 · Answer

Now we have an equation in one variable that we can solve with algebra.

$6x + x = 420$

Add the left side:

$7x = 420$

Divide both sides by 7:

$x = 60$

We let x = number of angelfish, so the number of angelfish is 60.

Since the number of parrotfish is 6x, 6 * 60 = 360. There are 360 parrotfish.

mathstudent55 · Answer

Let's check our answer:
60 + 360 = 420
The total number of fish is correct, 420.
360 = 6 * 60
The number of parrotfish is indeed 6 times the number of angelfish.
Our answer is correct.

mathstudent55 · Answer

In conclusion:
In problems of this type, you need to pick a variable. Then represent the situation in the word problem as an algebraic equation using the variable. Then solve the equation. Then answer the question in words. Then check the answer in the original word problem to make sure it is correct.