in this question i was using the Formula W= #rt and it gave me a different answer what are the specific terms in the question that tell us weather to use number of workers or not

Let R be the rate of work of a pump. Let W be the work of filling the complete tank.

Rate of work = Work done / Time taken … (1)

Condition 1 → (Rp + Rr + Rt) = \frac{W}{5} … (2)

Condition 2 → (Rp + Rr) = \frac{W}{7} … (3)

Now since you know Rp + Rr substitute it in equation 2 to get Rt = \frac{W}{5} - \frac{W}{7} = \frac{2W}{35} … (4)

If T works alone, from 1, we know Rt = \frac{W}{Time taken}. Substitute Rt from equation 4 and simplify.

in condition two shouldn’t it be **W / 7**

Yea sorry. changed it!