Mike and Dena are painting a fence. if Mike has done 1/3 of the job and Dena has done 2/7 of the job, what fraction of the job is left to be finished?

8/21

Step-by-step explanation:

The total job is 1

Mike has done 1/3 and Dena has done 2/7 of the job We still need to do x of the job to complete it

1/3 + 2/7 + x = 1

We need to get a common denominator 3*7 = 21

Multiply each side by 21

21 (1/3 + 2/7 + x) = 1*21

21 (1/3) + 21 * (2/7) + 21x = 21

7 + 3*2 + 21x = 21

7+6+21x = 21

13+21x = 21

Subtract 13 from each side

13-13+21x=21-13

21x = 8

Divide each side by 21

21x/21 = 8/21

x = 8/21

We need to complete 8/21 of the job