Answer:
25
Step-by-step explanation:
25 should be chosen as the common denominator. 5 is a possible common denominator because the other fraction has a denominator of 5 and 25 is divisible by 5, however, the numerator cannot be evenly divided by 5. Attempting to do so would cause a much more difficult equation. On the other hand, the denominator 5 can be changed to 25 by multiplying by 5, and 4 can also be changed by multiplying by 5.
4/5 x 5 = 20/25
6/25 - 20/25 = -14/20 = -7/10
