look in description

Question

A tip jar contains x one-dollar bills and y five-dollar bills. There are 42 bills in the jar, and the total value is $90.00. how many one-dollar bills and how many five-dollar bills are in the tip jar?

 

system=??

 

Answer 1

 This is a classic substitution equation. 

You need to set up a system of equations first. You have two equations based upon the information provided. 

X +Y =42

1x +5y =90

 

first,   Solve the simpler equation for Y (or X,   But I chose Y). This will give you. Y=42-X

Second, substitute the Y variable you just arrived at, into your second equation. 

1x + 5(42-x)=90

1x + 210 -5x =90

x=30

 

lastly, substitute x into the original formula that you started with.

30+Y=42

Y=12

 

hope it helps! Good luck.