Question

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?​

Answer 1

8/21

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