let x be the number of quarters, and y be the number of dimes.
we know that x + y = 29
then we are also given that
y = 5 + 3x
so we can solve for x and y:
plug y into the first equation:
x + 5 + 3x = 29
4x = 24
x = 6
and
y = 5 + 3*6 = 23
I have 6 quarters and 23 dimes