Question

solve simultaneous algebraically
x-y=6
2x+3y=7

Answer 1

time 3 to the top which equals, 3x-3y=18 then add both equations which then get one equation: 5x=25

Answer 2

(3x-3y=18)
+(2x+3y=7)
=5x+0= 25

x=5

Answer 3

or i guess you could solve for x or y in the top equation

x=6+y then plug into the second equation

Answer 4

x-y=6
2x+3y=7
x=6+y
2(6+y)+3y=7
12+5y=7
y=-5
x=1

Answer 5

@Nick, you have a wrong calculation:
\[12+5y=7 \Rightarrow 5y = -5 \Rightarrow y = -1\]
then:
\[x = 6+y \Rightarrow x = 6+(-1) \Rightarrow x = 5\]