Data Sufficiency

Hello,

Can you please tell me if the answer and the way I am calculating the slope is correct?

Is line a's slope less than b's?

(1) Lines a and b intersect at point (10,1).
(2) Line a's y-intersect is greater than b's.

OA: C


Now 1 and 2 are in-suff

Combining: Suff


In Image_1 I was calculating the slope as follows:

Slope of A = 4/12 = 1/3 = 0.3
Slope of B = 3/15 = 1/5 = 0.2

Since A and B are going from right to left, their slopes are negative

i.e. Slope of A = -0.3 and Slope of B = -0.2

Slope of A is less than Slope of B


In Image_2:

Slope of A = 2/6 = 1/3 = 0.3
Slope of B = 4/8 = 1/2 = 0.5

Since A and B are going from right to left, slope is positive

i.e. Slope of A = 0.3
and Slope of B = 0.5

Slope of A is less than Slope of B


Can you please tell me if my understanding of slope is correct?

Thanks,
Sri