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