Question

How this answer came pls explain this answer... for this question

Answer 1

A=x km/hr
b=y km/hr
from first condition
8x=8y+80
8x-8y=80
dividing eq by 8
x+y=10
from second condition
x+y=80
adding both
x+y=10
x+y=80
2x+0=90
2x=90
x=45
putting value
45-y=10
45-10=y
y=35
speed of car A is 45km/hr
speed of car B is 35km/hr