Algebra 1 unit8

Question

7)You have a total of 21 bills,all of which are either $5 bills or $10 bills. The total value is $170. How many of each type of bill do you have?Write and solve a system of equations to solve the problem.

 

Answer 1

Let x = the number of $5 bills

Let y = the number of $10 bills

x + y = 21      x = 21 - y

5x + 10y = 170

5(21 - y) + 10y = 170

105 - 5y + 10y = 170

5y = 65

y = 13

x = 21 - 13

x = 8