Area of Rectangle = length times width
lets say length = 2x-4
width = x+5
Note: you can switch these around, width could be 2x-4 and length could be x+5, it doesnt matter.
With that being said:
length * width = area
(2x-4)(x+5)=area
FOIL (First Outer Inner Last)

Simplify:
Any number that ends with a 0 or a 5 would be a multiple of 5 because as you multipy numbers by 5 you start to see a pattern in the ones place of 5,0,5,0,5,0,5,0,... And so on forever
When simplifying you need to be able to divide both the top and bottom number in the fraction by one of their factors. A number will be fully simplified when they become a prime number or have one as the numerator.
X = 7. 7 x 4 = 28 and 28 + 3 = 31.
31>27