SOLUTION: I am having difficulty setting up my word problems. What is the best way for me to figure out how to write equations, especially like the one below: The Math club bought 15 pizz

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: I am having difficulty setting up my word problems. What is the best way for me to figure out how to write equations, especially like the one below: The Math club bought 15 pizz      Log On


   

Question 286537: I am having difficulty setting up my word problems. What is the best way for me to figure out how to write equations, especially like the one below:
The Math club bought 15 pizzas. Cheese pizzas cost $9 each and specialty pizzas cost $15 each. If the total cost is $189, how many of each kind was ordered?
I came up with

$9x+$15y=$189
x+y=15
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
$9x+$15y=$189
x+y=15 or x=15-y
Now replace x with (15-y) in the first equation & solve for y.
9(15-y)+15y=189
135-9y+15y=189
6y=189-135
6y=54
y=54/6
y=9 $9 dollar pizzas were bought.
x=15-9=6 $15 dollar pizzas were bought.
Proof:
9*15+6*9=189
135+54=189
189=189