In Problem 10, 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 30 pages of economics and 70 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) 4E + S = 190.
B) E + S = 70.
C) E + S = 100.
D) + S = 50.
E) All of the above.

Question

Quizplus · Accepted Answer

The time taken to read 40 pages of economics and 30 pages of sociology is the same as the time taken to read 30 pages of economics and 70 pages of sociology. This can be expressed as 4E + 3S = 3E + 7S, which simplifies to E = 4S. Substituting E = 4S into the equation for the time to read 40 pages of economics and 30 pages of sociology gives 4(40) + 30 = 190.

In Problem 10, If in the Same Amount of Time