Question

Anna has 12 bills in her wallet, some $5 and some $10. The total value of the bills is $100. HOw many of each bill odes Anna have?

How do i solve these type of problems my quess was this but i don't know if i'm correct.

5(x) + 10(y) = 100
5(0) + 10y = 100
10y = 100
--- ---
10 10

y = 10

5(x) + 10(10) = 100
5x + 100 = 100
-100 -100

5x = 0
--- ---
5 5

x = 0

to check is :

5(0) + 10(10) = 100
0 + 100 = 100
100 = 100


you have the intercepts ok.

but its asking about how many of each so is my answer correct or what am i doing wrong.

Answer 1

5(x)+10(12-x)=100
5x+120-10x=100
-5x=-20
5x=20
x=4(no of 5dollar bills)
12-4=8(no of10dollar bills)