
Bradford T. answered 04/28/23
Retired Engineer / Upper level math instructor
Let n and p be the number of nickels and pennies.
p = n+80
0.01p + 0.05n = 7.40
Multiply both sides of the equal sign by 100
p+5n = 740
substituting for p
n+80 + 5n = 740
6n = 660
n = 660/6 = 110 nickels
p = n+80 = 190 pennies