A dime is a ten cent coin while a quarter is a 25 cent coin. The total of the money should be $8.40. Let x be the number of dime and y be the number of quarter. The equation that would best represent the given problem is,
0.1x + 0.25y = 8.40
x + y = 45
The values of x and y are 19 and 26, respectively. Thus, there are 19 dimes and 26 quarters.