Question 1176736


let dimes be {{{d}}} and quarters {{{q}}}

if he has {{{73}}} coins altogether, we have

{{{d+q=73}}}
{{{d=73-q}}}....eq.1

{{{1d}}}=${{{0.10}}}
{{{1q}}}=${{{0.25}}}

if he has ${{{13.75}}}, then

{{{0.10d+0.25q=13.75}}}.....substitute {{{d}}} from eq.1

{{{7.3-0.10q+0.25q=13.75}}}

{{{0.15q=13.75-7.3}}}

{{{0.15q=6.45}}}...both sides multiply by {{{100}}} to get rid of decimals

{{{15q=645}}}

{{{q=645/15}}}

{{{q=43}}}

go to eq.1

{{{d=73-q}}}....eq.1, substitute {{{q}}}
{{{d=73-43}}}
{{{d=30}}}

Andrew has
{{{30}}} dimes 
Andrew has
{{{43}}} quarters