Kevin and Randi have a jar containing 63 coins, being either quarters or nickels. they total

$9.15. how many quarters and nickels are there?

Yess, such fun so

q=number of quarter

n=number of nickles

q+n=63

9.15=915 cents

25 cents=1 q

5 cents=1 n so

915=25q+5n

915=5 (5q+n)

divide by 5

183=5q+n

we also have q+n=63

subtract q from both sides

n=63-q

subsitute 63-q for n in second equation

183=5q+63-q

add like terms

183=4q+63

subtract 63 from both sides

120=4q

divdie by 4

30=q

there were 30 quarters

subsitute

63=30+n

subtract 30

33=n

30 quarters

33 nicles