To solve problem 1 what you need to do is figure out how many miles the girls have walked so far and then subtract that from the total distance they must complete.
3/4-(3/10+1/4)
Step 1:Change the denominators so that way they are all the same
3/4=15/20
3/10=6/20 15/20-(6/20+5/20)
1/4=5/20
Step 2: Begin solving the problem
6/20+5/20=11/20
15/20-11/20=4/20
Step 3: Simplify your answer
4/20=1/5
Step 4 (is optional): Write your answer in a complete statement
The three girls walk 1/5mile together to school
Answer: A
I hope this is correct and if not I apologize for giving false information.