If in the Same Amount of Time That It Takes

Multiple Choice

if in the same amount of time that it takes her to read 40 pages of economics and 30 pages of sociology, Martha could read 20 pages of economics and 90 pages of sociology, then which of these equations describes combinations of pages of economics, E, and sociology, S, that she could read in the time it takes to read 40 pages of economics and 30 pages of sociology?

A) E + S = 110.
B) E/2 + S = 50.
C) 3E + S = 150.
D) E + S = 70.
E) All of the above.