-3x + 4y = 12
x - y = 1....x = y + 1
-3(y + 1) + 4y = 12
-3y - 3 + 4y = 12
-3y + 4y = 12 + 3
y = 15
x - y = 1
x - 15 = 1
x = 1 + 15
x = 16
one solution (16,15)
Step-by-step explanation:

Answer:
A. 19,70,91
Step-by-step explanation:
Interior angle =180
19+70+91=180
In order to answer that question, we need to know the scale of the map.
Without that information, no answer is possible.
I think you have it in the first part of the question ... the part you decided
not to post.
_________________________
OK. Now that you've provided the scale of the map,
answering the question is a piece-o-cake.
Use a proportion:
(1 inch on the map) / (4 miles on the ground) = ('x' on the map) / (17 miles on the ground)
you would do PEMDAS
you do -3 times 4. then you do that and devide by -3.