What binomial must be subtracted from 7t-5) so that the difference of the 2 polynomials is (5r+8) ?

1) Given binomials:

First binomial 7r - 5

Second binomial 5r + 8

2) To pass from 7r to 5r you have to subtract 2r, so the first term of the binomial to be subtracted is 2r

3) To pass form - 5 to + 8, you have fo subtract - 13

4) So the answer is 2r - 13, option b.