Question 253612
There are a few equations here. Let N = nickel, D = dime, and Q = quarter.
First, the money equation:
(i){{{5N + 10D + 25Q = 495}}}
Second,
(ii) {{{D = Q}}}
Third,
(iii) {{{N = 2D}}}
We want to get everything into the same variable. Turn everything into D. From substitution of (ii) and (iii) into (i), we get
(iv) {{{5(2D) + 10D +  25(D) = 495}}}
Solving for D, we get
(v) {{{10D + 10D + 25D = 495}}}
{{{45D = 495}}}
dividing by 45, we get
{{{D = 11}}
This means that
{{{N = 22}}}
and
{{{ Q = 11}}}