If 2x − 9y = 14 and 6x = 42 + y, what is the value of the product xy?
2x - 9y = 14
y = -42 +6x
2x - 9 (-42 + 6x) = 14
x= 7
y= -42 + 6 * 7
y = 0
(x,y) = (7,0)
xy= 0