Question 45290
You're absolutely right - you need to use 8 as your gcf...  So, with that let's focus on the 1/4 first...  1/4 Is going to be changed to 2/8 because it's equivalent to 1/4, yet has the denominator 8 (which is what you need.)  1/2 Will be changed to 4/8 because it's equivalent to 1/2, and 1/8 will be left alone because it already has 8 as it's denominator...  So, now we have to add 2/8, 4/8 and 1/8 together....  What do we get?  7/8...  There's your answer.