Question

MIkeeeeeeee12222
can somebody please help i dont understand thiss

Suppose you have just enough money, in coins, to pay for a gallon of milk priced at $2.40. You have 12 coins, all quarters and dimes. Let q equal the number of quarters and d equal the number of dimes. Which system models the given information?

Answer 1

Okay, so
\(\normalsize\color{blue}{ \rm { q+d}=12 }\) this is the equation of number of coins
\(\normalsize\color{blue}{ \rm { 0.25q+0.10d}=2.40 }\) and this is for the cost of the milk.

Answer 2

Makes sense, right ?

Answer 3

pretty much @SolomonZelman

Answer 4

Okay;) Well.... Ill post something long. Ready ?

Answer 5

yes

Answer 6

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Answer 7

@SolomonZelman ok now can we get back to the math problem?

Answer 8

YEs, sure...

Answer 9

At first, do you understand where I am getting the \(\normalsize\color{green}{ \bf {q+d=12 } }\) ?

Answer 10

Then,
\(\normalsize\color{blue}{ \rm {\color{red}{ 0.25}q+\color{red}{ 0.10}d=12 } }\) I am multiplying the number of quarters times 0.25, and the number of dimes times 0.10, THIS GIVES ME the cost.

Answer 11

it gives you the cost because each quarter is equals 25cents and each dime is equal to 10 cents and the 12 is the total of coins put all together right?

Answer 12

Oh yeah... can you solve the system, or need a little assistance for that part ? Or you don't need to solve the system ?

Answer 13

i need a little assistance

Answer 14

With solving the system of equations ?

Answer 15

im sorry im late but yes pleasee

Answer 16

Subsitution:

Isolate d from the second equation

\[d=\frac{ 2.4-0.25q }{0.1}\]

Subsitute d into the first equation, then solve:

\[q+\frac{ 2.4-0.25q }{ 0.1 }=12\]

Solve for d...

Then plug the value of d back into either equation(preferably the first one), then solve for q