Here x and y can have 7 possible values from 1-7.
Now, if any of the sums happen to be same we will get
3x + 7y = 3a + 7b, 0 < a,b,x,y < 8
3(x-a) = 7(b-y)
Happens only if b-y is a multiple of 3 and x-a is a multiple of 7. So, minimum value of x should be 8 as a is positive. But this is not possible and hence all the sums must be distinct.
The answer is 1. 49