The function c(x) = 3x − 4 determines how many cupcakes need to be purchased for a birthday party, where x is the number of kids at the party. The party planner uses d(c(x)) to find the amount of money to bring for the cupcake purchase. The function d(x) = 2x + 5. Solve for how much money to bring when there are 7 kids at the party.

Question

anonymous · Answer

Options :
17

 19

 25

 39

anonymous · Answer

Basically what I don't understand is the solving, is it like the f(x) g(x) thing?

anonymous · Answer

@Ab590 @LaceyLeanne @dmezzullo @Country_Boy_Jonathan.

anonymous · Answer

Ok. If x is the amount of kids and there are 7 kids...Than change x to a 7!

anonymous · Answer

I'm guessing the c(x) is just a filler?

anonymous · Answer

I think the answer is either 19 or 25..

austinl · Answer

We have two individual functions.

$c(x) = 3x − 4$, how many cupcakes to bring

$d(x) = 2x + 5$, how much money for a certain number of cupcakes


To determine how much money the party planner needs means that they use the function
$d(c(x))$

Which is,

$d(c(x))=2(3x-4)+5=6x-8+5=6x-3$

If there are seven kids, that means,
$d(c(7))=6(7)-3=\color{blue}{39}$

anonymous · Answer

@austinL Oh okay.. thanks so much for explaining it T_T

austinl · Answer

You are very welcome!