Question 160907
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{{{D+N=54coins}}} -----------------------> EQN 1
In EQN 1 we get,
{{{D=54-N}}} ----------------------------> EQN 2
Also,
{{{0.10D+0.05N=3.80}}} ------------------> EQN 3
Subst. EQN 2 in EQN 3:
{{{0.10(54-N)+0.05N=3.80}}}
{{{5.4-0.10N+0.05N=3.80}}}
{{{5.4-3.80=0.10N-0.05N}}}
{{{1.60=0.05N}}} ------> {{{cross(1.60)32/cross(0.05)=cross(0.05)N/cross(0.05)}}}
{{{N=32coins}}} number of Nickels (ANSWER)
For D, via EQN 2:
{{{D=54-32=22coins}}} number of Dimes
Check via EQN 3:
{{{0.10(22)+0.05(32)=3.80}}}
{{{2.2+1.60=3.80}}}
{{{3.80=3.80}}}
Thank you,
Jojo</pre>