9x - 2y = 11 ... (i)
5x - 2y = 15 ... (ii)
Subtracting equation (ii) from (i) we get;
4x + 0 = -4
4x=-4 , x = -1
Replacing x = -1 in equation (i) we get;
9(-1) - 2y = 11
-9 - 2y = 11
-2y = 20
y = 20 ÷ -2 = -10
The solution to the system of equations is (-1,-10).
Gallons per day.......gallons / day.....so u put the gallons over the number of days, then divide
(1/2) / 6 = 1/2 * 1/6 = 1/12 of a gallon per day <==
To graph it, just graph

and

and see where they intersect
I would like to solve it by using math and not graphing
if you don't want to see the math, just don't scroll down
the graphical meathod is above, first line, just read it
hmm
multiply both sides by -1

multiply both sides by



minus 1 from both sides and minus 6(3^x) from both sides

use u subsitution

we can rewrite it as

now factor
I mean use quadratic formula
for

so for 0=u^2-16u-1, a=1, b=-16, c=-1


remember that u=3^x so u>0
if we have u=8+√65, it's fine, but u=8-√65 is negative and not allowed
so therfor


if you take the log base 3 of both sides you get

if you use ln then

then
Formula:
Total hours ÷ hour per day
14 ÷ 3.5 = 4.
The answer is 4.
He commuted 4 days for the city.