For how many ordered pairs of positive integers (x,y) does the equation 1/x + 2/y = 2/5 hold?
1/x + 2/y = 2/5
(y + 2x) / (xy) = 2/5 cross- multiply
5 ( y + 2x) = 2(xy)
5y + 10x = 2xy
2xy - 5y = 10x
y( 2x - 5) = 10x
y = (10x) / (2x - 5)
When
x = 3 y = 30
x = 5 y = 10
x = 15 y = 6
