Respuesta :
n=nickels
d=dimes
n+d = 30
n+18 = 30
n = 30-18
n = 12 (number of nickels)
therefore Mary has 12 nickels
d=dimes
n+d = 30
n+18 = 30
n = 30-18
n = 12 (number of nickels)
therefore Mary has 12 nickels