The perimeter of the rhombus is 28 inches.
The numbers they are looking for are numbers that are simple but made up. For example, start with 0. Plug 0 in for x, so the corresponding value of y is 10. For a second value, you could do 2. When x=2, y=11, etc. So essentially, put in some simple numbers for x, and solve for y. :)
X = 4/15 or 0.26
First add the numbers on the left side of the equation.
0.72 = 0.8 - 0.3x
Then move the variable to the left as well.
0.3x + 0.72 = 0.8
Move the constant to the right by subtracting.
0.3x = 0.8 - 0.72
Subtract the numbers
0.3x = 0.08
Divide both sides by 0.3.
And that should yield your answer.
Hope this helps. ^^
If 1/10 of the tank is filled in 1/5 of an hour, then multiplying both of those by 5 you would get 5/10 of a tank being filled in a full hour, or answer choice A. Hope this helps! By the way, sorry for the incorrect answer a couple years ago :)