Answer:
2.- 100
Step-by-step explanation 1:

↑ As we can see, the only common multiple between 4 and 25 that is given to is 100.
Step-by-step explanation 2:

↑ Another way of knowing the answer is by using a fraction solving method. As we can see, the denominator is once again 100.
Hope it helped,
BiologiaMagister
20 - (4xn) = 4 is the equation