A-3b=9
a=b-3
b-3-3b=9
-2b-3=9
-2b=12
2b=-12
b=-6
a=-6-3
a=-9
Solution: (-9,-6)
----
Check:
-9=-6-3
-9=-9
TRUE
We need slope of all lines ?
Slope of JK:-

Slope of KL:-

Slope of JL

if you do 14-4 which is equal to 10
Answer:
L = 3W + 3.
Step-by-step explanation:
Twice the width = 2W,
Adding 3 gives 2W + 3.
4(x+3)=7
The mistake is with his final answer, he wrote down 4x=1.
When you do 4(x)4(3), the answer is completely different from what Andre said. He did wrong calculations.
4x3=12
7-12= -5
Which means it should be 4x=-5 as the final answer.