What 30 coins make up 0.78 cents

28 Pennies and 2 Quarters or 18 Pennies and 4 Dimes.

Step-by-step explanation:

Assuming that we are using the American currency.

First we need to break down the different equivalences of each coin.

1 Penny = 1 cent 1 Nickel = 5 cents 1 Dime = 10 cents 1 Quarter = 25 cents

One combination would be:

28 Pennies and 2 Quarters:

28 Pennies = 28 Cents

2 Quarters = 50 Cents

50 + 28 = 78 Cents.

Another combination would be:

18 Pennies = 18 Cents

12 Nickels = 60 Cents

18 + 60 = 78 Cents.