The LCM will never be less than the GCF.
1394
HCF of 17 and 68 is 17 ..( Lowest Prime factor ) LCM Of 102 and 476 is 7*2^2*3*17 which is 1428 .. ==> Sum of HCF and LCM are 1428+17= 1445 .
It is: 34+7140 = 7174
14 and 21 have a sum of 35 and an LCM of 42
They are: GCF = 5 and LCM = 325 and the sum is 5+325 = 330
The sum is 335.
84
Look at both of the numbers' prime factors, and put them into a sum. The LCM multiple is the answer you get from that.
16 and 3
16 and 3
16 and 3
The numbers are 34 and 51, which have a sum of 85 and their LCM is 102, the multiple of the highest power of their prime factors 2, 3, 17.