Three numbers which are co-prime to each other are such that the product of the first two is 551 and that of the last two is 1073. The sum of the three numbers is:

Three numbers which are co-prime to each other are such that the product of the first two is 551 and that of the last two is 1073. The sum of the three numbers is: Correct Answer 85

Since the numbers are co-prime, they contain only 1 as the common factor.
Also, the given two products have the middle number in common.
So, middle number = H.C.F. of 551 and 1073 = 29
$$\eqalign{ & {\text{First}}\,{\text{number}} \cr & = {\frac{{551}}{{29}}} \cr & = 19 \cr & {\text{Third}}\,{\text{number}} \cr & = {\frac{{1073}}{{29}}} \cr & = 37 \cr & \therefore {\text{Required}}\,{\text{sum}} \cr & = {19 + 29 + 37} \cr & = 85 \cr} $$