Answer:
A dime is worth 2 nickels.
let no of dimes be x
let no of nickles be y
so as per the data mentioned in the question , x=2*y-10
total amount = $2.75
so total amount should comprise of nickels and dimes
x*dimes + y*nickels = $2.75
x*( 2 nickels)+ y *nickels = $2.75
=> nickles( 2x+y) = $ 2.75
but 20 nickels = 1 dollar
nickles(2x+y) = 2.75*20 nickels
cancelling nickles on both sides
2x+y = 55
already we know that x= 2y-10
so 2(2y-10) +y= 55
4y-20+y=55
5y -20 =55
add 20 on both sides
5y-20+20=55+20
5y=75
divide with 5 on both sides
5y/5 =75/5
y= 15
so x= 2y-10
x= 2*15-10
x= 30-10
x= 20
so # of dimes =20
# of nickels =15
