A coin purse contains 18 points in nickels and dimes. The coins have a total value of 1.15. Find the number of nickels and dimes in the coin purse

Answer 1

I'm going to do away with the pesky decimals by dealing with cents (multiplying by 100).

n + d = 18

5n + 10d = 115

The easiest way is to solve the first equation for either of the lone variables. I'll do d.

d = 18 - n

Now, suuuuubstitite! Expressions on either side of the equal sign are the same.

5n + 10(18 - n) = 115

5n + 180 - 10n = 115

-5n = -65

n = 13 nickles

Substitute your found value.

d = 18 - 13

d = 5 dimes

Answer 2

1.15=.05n+.10d

n+d=18

13n+5d