The two angles are corresponding angles, so they are congruent (due to the horizontal lines being parallel)
x+15 = 102
x+15-15 = 102-15 .... subtract 15 from both sides
x = 87
1/40+1/50=1/n
5/200+4/200=1/n
9/200=1/n
9n=200
n=200/9 minutes for both of them to prepare the field
☺☺☺☺
Oh. I thought you meant 3-6, not questions 3 through 6. Sorry :(
Answer:
-4 + -2 = -6
Step-by-step explanation:
Assuming you meant is

The answer would be :




Hope this helps !
Photon
However, your equation seems weird :o