Given 2 equations on the variables x and y, solve for x and y. The first line of input contains N, the number of test cases. Each test case consists of two equations, each on a separate line. An empty line separates cases. An equation consists of two or more terms separated by addition, subtraction, or equality. A term is an integer, or a variable name (x or y) optionally preceded by a minus sign or an integer. There is exactly one equality. All operators are surrounded by spaces, and there are no spaces within terms. For each case, print two lines, giving the values of x and y as rationals in simplest terms. If x or y has no unique rational value such that both equations hold, print "don't know" for its value. Print an empty line between cases.
7 2x + 3y = x 5 = x + y + 3 2x + 3y = 0 10x = -15y 2x + 3y = 0 10x = -15y + 1 x = 1 3x = 6y 2x = 3x + -x + y x + y = x + y 2x = -3 -2y = 3 1 = 2 x = 3
3 -1 don't know don't know don't know don't know 1 1/2 don't know 0 -3/2 -3/2 don't know don't know