Question 153438
Remember:
Number of dimes = {{{x}}}
Number of quarters = {{{y}}}
So, {{{x+y=40coins}}} ----------------------------------------> eqn 1
Also,
{{{0.10x+0.25y=4.90}}} ---------------------------------------> eqn 2
In eqn 1 we get, {{{y=40-x}}}, substitute this in eqn 2:
{{{0.10x+0.25(40-x)=4.90}}}
{{{0.10x+10-0.25x=4.90}}}
{{{10-4.90=0.25x-0.10x}}}
{{{5.10=0.15x}}} --------> {{{cross(5.10)34/cross(0.15)=cross(0.15)*x/cross(0.15)}}}
{{{x=34}}} --------------------------------------> no. of dimes
In eqn 1:
{{{34+y=40}}} --> {{{y=40-34=6}}} ----------------> no. quarters
In doubt? Go back eqn 2:
{{{0.10(34)+0.25(6)=4.90}}}
{{{3.40+1.50=4.90}}}
{{{4.90=4.90}}}
</pre><font size=4><b>Thank you,
Jojo</pre>