Seven nickels and dimes

Question

seven nickels and dimes have a total value of $.45.

how many are there each?

Answer 1

x is nickel variable

y is dime variable

 

.05x+.10y=.45

x+y=7

 

y=7-x  (solve for y)

 

 

 

.05x+.10(7-x)=.45     (plug y equation in for y in top equation '.05x+.10y=.45')

.05x+.7-.1x=.45        (distribute and combine like terms)

 

x=5

 

5+y=7          (plug 5 into original equations)

y=2              (solve for y)

 

 

2 dimes

5 nickels