Problema Solution

Mike has $1.55 in nickels and dimes. He has 7 more nickels then dimes. Find the number of each kind of coin. Let n = number of nickels and d = number of dimes.

Answer provided by our tutors

1 nickle = 5 cents

1 dime = 10 cents


let


n = the number of nickels, n>0, n is integer

d = the number of dimes, d>0, d is integer


Mike has $1.55 = 155 cents in nickels and dimes:


5n + 10d = 155 divide both sides by 5


n + 2d = 31


He has 7 more nickels then dimes:


n = d + 7


by solving the system of equations


n + 2d = 31

n = d + 7


we find


n = 15 nickles


d = 8 dimes


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Mike has 15 nickles and 8 dimes.