The answer is
b= 28/5 or 5.6 in decimal form

Cross multiplying, we get:

Thus the value of y for given proportion is 18.
Your answer would be 0 and -4. When you plug in 2x - 4 in for the y of the second equation and solve, you get x = 0 and y = -4.
I think yes. If not my bad.
To answer this question and you will use exponents.
When you fold your paper three times, it is represented as two cubed or 2^3.
When you for your other sheet of paper two times, it is represented as two squared or 2^2.
Put Both of these together and you have 8+4 which equals 12.
It will take 12 layers of paper.