Find the gcf of the first two terms and the gcf of the last two terms of the polynomial. 5h^3+20h^2+4h+16

The GCF of the first two terms: 5h²
The GCF of the last two terms: 4

5h³ and 20h² 

Both of these terms are divisible by 5. (constant)
Both of these terms also have at least 2 h's. (variable)

4h and 16

Both of these terms are divisible by 4. 
Only one term has a variable, so that has to be left out.