SimaQ wrote:

I choose C...

simplify the given equation to x+y=14-xy

now you see that x+y cannot equal 3, 5 or 9 because in those cases xy would have to be odd number, which is impossible if both numbers are intergers....

So look at C and D....

xy could equal 8 or 6.... however plug in values....

2+3=14-6....cannot hold

4+2=14-8...holds....

Do not know a better way...

I don't understand why x+y can't be 3, 5 or 9.

if x+y=3, so xy=11 (11 * 1)

if x+y=5, so xy=9 (9 * 1 or 3 * 3)

if x+y=9, so xy=5 (5 * 1)

Where am I wrong?