Question 1203578

nickels: {{{n}}} 
dimes: {{{d}}} 

{{{1n}}}=${{{0.05}}} 
{{{1d}}}=${{{0.10}}} 

Sarah has ${{{5.25}}}

{{{5.25=0.05n+0.10d}}}...eq.1

If she has {{{3}}} times as many nickels as dimes, we have

{{{n=3d}}}.....eq.2

{{{5.25=0.05*3d+0.10d}}}...solve for {{{d}}}

{{{5.25=0.15d+0.10d}}}

{{{5.25=0.25d}}}.....both sides multiply by {{{100}}}

{{{525=25d}}}

{{{d=525/25}}}

{{{d=21}}}

go to eq.2, substitute the number of dime

{{{n=3*21}}}

{{{n=63}}}

Sarah have {{{63}}} nickels and {{{21}}} dimes.

check:

{{{63*0.05+21*0.10=3.15+2.1=5.25}}} which verifies our solution