Question

Christopher is 4 times as old as Michael. Ten years ago, Christopher was 9 times as old as Michael.How old is Christopher now?

Answer 1

Are you able to turn the sentence into an equation?

Answer 2

yeah

Answer 3

i think that is what im supposed to do, but im having trouble setting it up

Answer 4

Okay, no problem. Do you have a guess as to how you would start?

Answer 5

4x-10 is this one side of the equation?

Answer 6

Can you write an equation for right now? Let's say time = 0 right now.

Answer 7

yeah

Answer 8

Use C and M for your variables.

Answer 9

okay but how would i set it up?

Answer 10

"Christopher is 4 times as old as Michael." Write that algebraically.

Answer 11

4m ?

Answer 12

What is 4M?

Answer 13

4 times michaels age

Answer 14

4 * M

Answer 15

Right. But you need an equals sign and something on the other side. For example, if steak is 10 times heavier than rice, steak = 10 * rice, which as a formula would be S = 10R

Answer 16

So how would you write a formula for "Christopher is 4 times as old as Michael?"

Answer 17

4m=10(4x-9) ? i have no idea ._.

Answer 18

That's okay. Not to worry. It's C = 4M

Answer 19

Does that make sense?

Answer 20

That is a perfectly valid statement for right now. Now, the tougher part, you need to write a formula for 10 years ago.

Answer 21

oh okay i know that 10 has to be outside the parenthesis

Answer 22

no wait..

Answer 23

does 9 go outside?

Answer 24

because it says 9 times as old as Christopher

Answer 25

On the side where parentheses matter, the 10 will actually need to go inside.

You need to write an equation for the second statement which uses the variables for their current ages. That might sound complex, but it's as simple as:

My current age might be x.

I can say that 10 years ago, my age was x - 10. It doesn't matter what x represents; x - 10 is valid no matter what.

Answer 26

ohhh

Answer 27

Yes, right! The 9 goes outside.

Answer 28

okay so it would be 9(x-10) ?

Answer 29

Yes! But what is x?

Answer 30

i mean c. im using x instead of c

Answer 31

Remember, you need an equal sign, and stuff on both sides of it.

Answer 32

Okay, we can use x instead of C. But then what are we using instead of M?

Answer 33

Remember, for now, we are keeping their ages separate.

Answer 34

i guess we can use y or m but i like x instead of c

Answer 35

Sure. Okay, so in the formula I gave before, x = 4y

Chris (x) is 4 times older than Michael (y) right now.

Answer 36

So now, we need to do our "10 years ago" formula.

Answer 37

would it be the one i mentioned before?

Answer 38

Yes, but you used x. It should be y.

Answer 39

And you need your full formula.

Answer 40

But you're doing great.

Answer 41

@sws._. Mention me if you feel like continuing. I'd like to help you learn this so you can do your other 11 questions.