4/13=-2b/13=6b/26

Answer 1

There is something wrong with that. Did you mean to type two = signs?

Answer 2

the second one is an addition sign

Answer 3

Hint: clear the fractions.

4/13 = -2b/13 + 6b/26
4 = -2b + 3b (multiplying both sides by 13)
b = 4