It will take 20 states.
using cross product method we can implement AND and OR operations
Divisible by 4 ={q0,q1,q2,q3} q3 final state
Divisible by 5 ={w0,w1,w2,w3,w4} w4 final state
4x5 ={q0w0,q0w1,.....q3w3}
20 states.
To implement OR we need to make final states of all the states which have either q3 or w4 in them.