Let

a = the number of eggs that April had

p = the number of eggs that Peter had

m = the number of eggs that Marsha had

April and Peter had a combined total of 25 eggs:

a + p = 25

Peter and Marsha had a combined total of 23 egg:

p + m = 23

April and Marsha had a combined total of 24 eggs:

a + m = 24

We have the following system of equations:

a + p = 25

p + m = 23

a + m = 24

........

........

a = 13 eggs

p = 12 eggs

m = 11 eggs

April had 13 eggs.

Peter had 12 eggs.

Marsha had 11 eggs.