Y and x have a relationship that is directly proportional;
y = 7 when x = 2
when y = 21 and x = ?
y : x
7 : 2
if we multiply 7 wit 3, the answer is 21
3 x 7 : 2 x 3
21 : 6
So, when y = 21, x = 6
First we have to find how much they spent on each gallon.
To find out how much Carly paid for each gallon we have to divide her total price by haw many gallons she got.
$17.50/7=$2.50 per gallon
Likewise we do the same for Jade
$45/15=$3
So the answer will be Jade paid more per gallon than Carly
Simplifying
7x + -10x + 18 + 2x = -5
Reorder the terms:
18 + 7x + -10x + 2x = -5
Combine like terms: 7x + -10x = -3x
18 + -3x + 2x = -5
Combine like terms: -3x + 2x = -1x
18 + -1x = -5
Solving
18 + -1x = -5
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '-18' to each side of the equation.
18 + -18 + -1x = -5 + -18
Combine like terms: 18 + -18 = 0
0 + -1x = -5 + -18
-1x = -5 + -18
Combine like terms: -5 + -18 = -23
-1x = -23
Divide each side by '-1'.
x = 23
Simplifying
x = 23
Since we know 14, but we don't know the other number, we use a variable. To do that, we look at the problem, then we figure out the unknown. The unknown is: A number. We know 14. Since "Triple" means 3, we can put the exponent 3 by X.
Therefore, the answer is 
.
