Question 164537
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{{{D+Q=15coins}}} --------------------> EQN 1
Also,
{{{0.10D+0.25Q=3.30}}} ---------------> EQN 2
In EQN 1, we get,
{{{D=15-Q}}} -------------------------> EQN 3
Subst, EQN 3 in EQN 2:
{{{0.10(15-Q)+0.25Q=3.30}}}
{{{1.50-0.10Q+0.25Q=3.30}}}
{{{0.15Q=3.30-1.50=1.80}}}
{{{cross(0.15)Q/cross(0.15)=cross(1.80)12/cross(0.15)}}}
{{{highlight(Q=12coins)}}}
Via EQN 3,
{{{highlight(D=15-12=3coins)}}}
In doubt? Go back EQN 2,
{{{0.10(3)+0.25(12)=3.30}}}
{{{0.30+3=3.30}}}
{{{3.30=3.30}}}
Thank you,
Jojo</pre>