-3x+14=4x-7 = x=3
The answer is x=3
4a + 7b = 38 -> (1)
9a + 7b = 68 -> (2)
Subtract (1) from (2),
9a - 4a + 7b - 7b = 68 - 38
5a = 30
a = 6
The formula for the slope is 



Hope this helps.
頑張って!
Answer:
none
Step-by-step explanation:
8-4=4
if every 2 years, 4 gallons disappear
then every 1 year, 2 gallons disappear
meaning that by 5 years there will be no substance left.
(5*2=10)
Slope = (8 -2) / (1 + 5) =6/6 = 1
Parallel lines, slope is the same
So the slope of any line parallel to the line containing (-5,2) & (1,8) is also equal 1