Let x be the number of quarters and y the number of dimes.....so...
x + y = 8 → y = 8 - x (1)
And the number of each type of coin times its value gives the total value
.25x + .10y = 1.25 (2) put (1) into (2) for y
.25x + .10 [ 8 - x] = 1.25 simplify
.25x + .80 - .10x = 1.25
.15x + .80 = 1.25 subtract .80 from each side
.15x = .45 divide both sides by .15
x = 3 this is the number of quarters
And using (1) y = 8 - x = 8 - 3 = 5 and this is the number of dimes
