Answer: Choice D) 
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Work Shown:

Explanation:
First I subtracted y/b from both sides. Then I multiplied both sides by 'a' to fully isolate x. You can optionally distribute the 'a' through to each term inside the parenthesis, but your teacher has chosen not to do this.
$160 (if uncle, granny, aunt, gave $100 in total) $260 if they gave $100 each
I would subtract the 2nd from the first one
so -4x - -2x = -2x
4y - 4y = 0
-20 - -2 = -18
-2x = -18
now I would divide that by -2 to get the value for x
so no we have x = 9
now you just have to substitute that into one of the equations and simplify to get y
-2 X 9 + 4y = -2
-18 + 4y = -2
4y =16
y = 4
Answer:
that scale factor is 2
Step-by-step explanation:
A the side is 2.5
B the same stop as side a but its 5
so 2.5 to 5 is multiply 2
Solution
-3b + 11 = -18 + 8b
-3b - 8b = -18 - 11
-11b = -29
b = 29/11