How man y kilometers traveled by bike ?

Total was 200
x+y=200
biking was 40 mor than bus
x=40+y
subsitute 40+y for x in other equation

x+y=200
40+y+y=200
40+2y=200
minus 40 both sides
2y=160
divide both sides by 2
y=80

sub back
x=40+y
x=40+80
x=120

120km biked
80km on bus

He is right i did this thing before

The answer would he -4,-2 because the points are just on the opposite side. since the x axis is +4 it's going to he -4 and since the y axis is -2 it stays there because whaen rotated it stays in the third quadrant