Question 1068593
d dimes
q quarters
{{{system(d+q=33,10d+25q=690)}}}



Simplify the money  (cents) count equation.
{{{2d+5q=138}}}


Elimination Method will be convenient as a next step.

{{{system(d+q=33,2d+5q=138)}}}


{{{system(2d+2q=66,2d+5q=138)}}}


{{{3q=72}}}


{{{highlight(q=24)}}}
-
{{{d=33-24}}}
{{{highlight(d=9)}}}