Answer to Question #291387 in Algebra for Rossy

Question

Find the value of (x+Y)if x+Y=5 and x-Y=15

Answer 1

$x+y=5, x-y=15$

Then

$$2x=20=>x=10$$

$$y=5-10=-5$$

$(x, y)=(10, -5)$

$$x+y=5$$