First of all, it is 2r

and it would be divide by 3.14 (pi) and then you should have the diameter. Then divide by 2 to find radius.
1+8=3r
9=3r
Both divided by 3
3=r
6)x-7+10 7)3+x+1 8)8x-16 9)x/2-9
So.. if we take the numerator to be say "a", then the denominator will be "a+3"

either of those two fractions will do