Question 480609
let dimes= d
value of dimes= 10d
let nickels=n
value of nickels=5n

{{{d+n=26}}} ---eq(1)

Convert $2.20 into cents so it is all in the same units. So as 1 dollar=100 cents.
2.20*100=220 cents  
{{{10d+5n=220}}}-----eq(2)


{{{d+n=26}}} ----eq(1) multiply by 5
{{{5d+5n=120}}}------eq(1)
{{{10d+5n=220}}}-----eq(2)
 change the signs for the eq(2)

So   
{{{5d+5n=120}}}------eq(1)
{{{-10d-5n=-220}}}-----eq(2)
--------------------
{{{-5n}}} ={{{-100}}}
{{{n=20}}}

Substitute n=20 in eq (1)

{{{d+20=26}}}
{{{d=6}}}

There are 20 nickels and 6 dimes