Question

if
in a science test , Devi scores 15 marks more than lixin .if Devi obtains twice as many marks as lixin find the number of marks lixin obtain
​

Answer 1

Answer:

let marks obtain by devi be x

let marks obtain by lixin be y

from 1st condition

x+15=Y

x-y=-15___1

from 2nd condition

2x=Y

2x-y=0_______2

multiplying equation 1 by 2

2x -2y=30___3

subtracting equation 3 and 2

=

2x-2y=30

-2x-y=0

__________

-y =30

y=-30

lixin obtain -30 marks