Afootball field is 100 yards long. tarik, the running back ,carried the ball 4 times in one drive for 15,21,2 and 12 yards. what fraction of the field did he advance his team with his runs?

First, with any word problem we need to figure out the important parts, so read it first and write down the things you find important.

100yards long
4 times
15
21
2
12

then we read it again and see what they are asking.

fraction of the field he advanced.

now, if we can, draw a picture

|----------------------------- 100 yards ------------------------------|
|-- 15 yds --|
|-- 21 yds--|
|-- 2 yds --|
|-- 12 yds --|

Now we can see that 100 is our total, and we need to figure out a fraction. so, let's use our total as a denominator

now, look at the picture. what goes on top? the number of carries? that doesnt give us the fraction of the field.

so what is left? the amount he ran!

so, we total those up.

that number needs to fit in our fraction, and the only open space is the numerator. So,

so, he moved his team half way down the field!

hope this helps with other problems