To find the dimensions you can just factor the equation...
x^2+4x-21
x^2-3x+7x-21
x(x-3)+7(x-3)
(x+7)(x-3) and this is equal to LW or WL
And note that x>3 for any possible solution.
A. -3x+5+7-4x
-3x-4x+5+7
-7x+12
-7x+12-5x+17
-7x-5x+12+17
-12x+29
B. -5*(x+2)= -5x-10
-6x-1+ (-5x-10)= -6x-5x-1-10=
-11x-11
I think the points given here are plotted linearly:
FGHI. in this case, we can tell that FG + GH + HI = FI. substituting to the expression devised, 2 units + GH + 1 unit = 7 units. This is equal to 3 units + GH = 7 units. GH is then equal to 4 units.