Suppose that a, b, and c are real numbers such that a/b = sqrt(10)/sqrt(21) and b/c = sqrt(14)/sqrt(15). Find a/c. Completely simplify and rationalize the denominator.
a/b * b/c = a/c
sqrt10 / sqrt 21 * sqrt 14/sqrt15 =
sqrt 140 / sqrt 315
2 sqrt 35 / 3 sqrt 35 = 2/3
