Solve for x.

3/8 = 12/x

x/5 = 10/12

4/6 = x/12

4/9 = 7/x

5/11 = 9/x

2/7 = x/21

7/8 = x/16

3/5 = 9/x

First one

remember

a/b=c/d also can be written as

ad=bc

so

first one can be rewritten as

3x=96

divide both sides by 3

x=32

2nd ones we can just times both sides by 5 to get

x=50/12

3rd one we times 12 both sides to get

x=8

4th one we translate to

4x=63

divide by 4

x=63/4

5th one we translate to

99=5x

divide by 5

99/5=x

6th one we times 21 both sides

6=x

7th one we times both sides by 16

14=x

last one we translate to

45=3x

divide 3

15=x