In the distributive property, we distribute something from the outside of the parentheses into the inside of the parentheses by multiplying . The reverse would be pulling a common factor from inside to the outside by dividing (factoring). In order to do this we have to find something common to everything in the parentheses. a, b, and c are not common, so let's look at the numbers... 5, 10, and 25 all have a factor of 5, so we need to divide each thing in the parentheses by 5 and bring it to the outside...
5a + 10b - 25c =
(5a/5)+(10b/5)-(25c/5)
5(a + 2b - 5c)
Done!
If you want to check it, do the distributive property and multiply 5 through the parentheses and you should get your original expression.
