+610 What is the ordered pair of integers $(x,y)$ for which $12x + 21y = 15$ and $21x + 12y = 51$?
+654 This is a system of equations problem.
To easiest way to solve this is first add both equations.
12x + 21y + 21x + 12y = 51 + 15
So 33 y + 33x = 66
x + y = 2
We can use x = 2 - y and plug this in to equation #1.
12 ( 2 - y ) + 21y = 15
24 - 12y + 21y = 15
y = -1
x = 3
The ordered pair you are looking for is (3, -1)
