Answer:
C
Step-by-step explanation:
3(3 + x) = 15 + x
Open bracket
9 + 3x = 15 + x
Collecting like terms
3x - x = 15 - 9
2x = 6
Dividing by 2
x = 6/2
x = 3
8 Tatami mats are needed to cover the floor.
Y/x=k
when y=9, then x= -3
9/-3=-3
⇒ k= -3
For example:
x+2y=7
6x+7y=2
__________
x=7-2y *
6*(7-2y)+7y=2 **
__________
x=7-2y
42-12y+7y=2
__________
x=7-2y
-5y=-40
__________
x=7-2y
y=8
x=-9
