You have 3 quarters, 5 dimes, 7 nickels, and some pennies.-If the ratio of dimes to the total number of coins you have is 1:3, how many pennies are there?

40 pennies

1 : 3 = 5d : 3q + 7n + 40p

= 50 : 75 + 35 + 40

1 : 3 = 50 : 150