There are x children
If she gives 20 stamps per child, she gives 20x stamps.
She then has 60 stamps left, so the total number of stamps is
20x + 60
If she gives 27 stamps per child, she gives 27x stamps.
She then has 4 stamps left, so the total number of stamps is
27x + 4
The two totals are describing the same stamps, so they must be equal.
20x + 60 = 27x + 4
-7x + 60 = 4
-7x = -56
x = 8
Answer: There are 8 children
