Working together, it takes two computers 5 minutes to send out a company's email. If it takes the slower computer 15 minutes to do the job on it's own, how long will it take the faster computer to do the job on it's own?

38+105= 143, 39+104=143, and you will find then adding the numbers on opposite sides, moving inwards yields the answer 138 every time. because of this, you’re going to multiply 138 times the number of pairs, which is 34. therefore, 34*138= 4692(i’m sorry if it’s the wrong numbers, but it’s the right concept)