GRE Math Problem 20

If x + y = a, y + z = b, and x + z = c. what is the average (arithmetic mean) of x, y, and z?
(A)
(B)
(C)
(D)
(E) a+b+c

Solution for GRE Math Problem 19:

Let X be Jordan's average of test scores after 5 tests. Then, he got total 5X points after 5 tests. If he gets 70 points after the next test, he'll have 5X+70 points. His average will be points. But it is given, that his average will be lower by 4 points. We have an equation:

5X+70=6X-24
X=94

Answer:(E) 94

See also these GRE problems: