First, write an equation system based on the problem For an instance, d stands for the number of dimes and n stands for the number of nickels. Dime's worth $0.10 and nickel's worth 0.05
"Pudge had 2.25 dimes and nickels" could be written as ⇒ 0.10d + 0.05n = 2.25 (1st equation)
"He had twice as many dimes as nickels" could be written as ⇒ d = n (2nd equation)
Second, solve the equation system Substitute d as n from the second equation to the first equation to find the number of nickels 0.10d + 0.05n = 2.25 0.10n + 0.05n = 2.25 0.15n = 2.25 n = 2.25/0.15 n = 15
Because d = n, therefore d = 15
Pudge has 15 coins of dimes and 15 coins of nickels
