Data Sufficiency

Problem 2)

1) x=y+1

This means that x and y are consecutive positive integers adding up to 77. The only consecutive integers that can do this are 38 and 39. Sufficient.

2)X and Y have the same tens digit.

The only numbers that add up to 77 and fit this description are also 38 and 39.
Sufficient.

I think the answer's D.

Problem 1:

Is m/r = x/y?
aka: is m*y = x*r?

1.
m/y = x/r
m*r = x*y

Not sufficient.

2.
(m+x)/(r+y) = x/y
(m+x)*y = (r+y)*x
m*y + x*y = r*x + y*X
m*y = r*x

Sufficient.

Answer is B.