What mistake did this guy make..........With the elimination method? I mean he got the right answer but messed up somehwere in the method

Start 5x - y =- 15
x + y = -3

step 1: 6x= -18
step 2 x= -3
step 3 5(-3) - y = -15
step 4 -15 - y = -15
step 5 y = -30
step 6 Solution is (-3, -30)

Question

What mistake did this guy make..........With the elimination method? I mean he got the right answer but messed up somehwere in the method

Start 5x - y =- 15
         x + y = -3

step 1: 6x= -18
 step 2             x= -3
 step 3             5(-3) - y = -15
 step 4             -15 -  y = -15
 step 5            y = -30
 step 6              Solution  is (-3, -30)

turingtest · Answer

it's not the right answer
he messes up between line 4 and 5
the -15's should cancel

geometry_hater · Answer

wow really the problem in my book says he got the solution correct....

turingtest · Answer

nope
y=0
try putting y=-30 into your equations you can see that it's not true
5(-3)-(-30)=15 (should be negative)

geometry_hater · Answer

alright then thanks for the help

turingtest · Answer

welcome