Answer:
32
Step-by-step explanation:
Linear pair means they form a line, or add to 180°.
2x − 5 + 4x − 7 = 180
6x − 12 = 180
6x = 192
x = 32
Answer:

Step-by-step explanation:
by using formula
, we get

Answer:
for the first photo the answer is 5x + 6(-x + 4) = 13
Step-by-step explanation:
if y equals to -x +4
then replace the y in this equation: 5x + 6y = 13 with this ( -x +4 ) its simple.
I cannot answer the other 2 photos at the moment but ill see if I can whenever else I have time.
As in negative or positive It would be negative