Question

how can i solve -1.5x+y=5
x+y=5

Answer 1

I would multiply the entire first equation by (-1)
so then your two equations would be
1.5x-y=-5
x+y=5
then you can use the combination method.
add em all up:
2.5x=0
x=0
then if x=0 then you can plug it in
0+y=5
y=5

if you want to use the substitution method, you can solve one equation for either x or y, i would choose the second for neatness
x+y=5
-x -x
y=5-x
then plug this new equation into the first one in lue of y
1.5x+x=5
2.5 x=5
divide, x still equals 0
then plug back in x and again you acheive y=5

Answer 2

akingnh, she's been gone for 13 minutes now, so you might as well give up on that.

Answer 3

she might come back! even so, try to help her out for future reference.