GMAT Test Prep: DS-64433780 GMAT Data Sufficiency

In the xy-plane, line a and line b have the same slope. If the y-intercept of line a is –1, what is the y-intercept of line b ?
(1) The x-intercept of line a is –1.(2) Line b passes through the point (10, 20).
Select one of the following answer choices