55+added=133
added=amount addeed per week times 6=6x
55+6x=133
minus 55 both sides
6x=78
divide both sides by 6
x=13
add 13 per week
y=13x+55
You know from trigonometry that AB = 15 units, so the area of the larger triangle ACB is (1/2)*15*15 = 112.5 units^2.
Then the area of triangle ADE is
.. (112.5 -62.5) = 50 . . . . units^2
The answer would be -15x+36. To solve this equation, you would first use distributive property and distribute the -9 to the values inside the parentheses (or multiply them). So, you would multiply -9 and x and -9 and -4 to get -9x+36-6x. Then, you combine like terms, which are -9x and -6x to get -15x. You can't simplify any further without knowing the value of x. Hope this helps!
@Texaschic101 you are correct .75 x 64 will indeed equal 48 sq feet. so your answer will be 64 tiles. hope this was of help!