Mx + 4y = 3t
mx = -4y + 3t
x = (-4y + 3t) / m or x = -4y/m + 3t/m
A slope of 1/2 means for every two units to the right we move up one.
We have to be careful here because the graphs don't always use the same scale for x and y.
The bottom left uses the same scale and does indeed go two units to the right for every unit up, so that one is the answer.
15, 18, 21
i don't know the other one, sorry
8x - 4y = 8
-4y = -8x + 8
y = -8x/-4 + 8/-4
y = 2x - 2, comparing to y = mx + c, slope m = 2
Slope = 2.
If you want to solve it the answer is 13...
If you want multiple ways to write that here are some:
3x4+2-1
3x4+1
12+2-1
12+1
Etcetera
