<span>Difference of squares method is a method that is used to evaluate the difference between two perfect squares.
For example, given an algebraic expression in the form:
can be factored as follows:

From the given expressions, the only expression containing two perfect squares with the minus sign in the middle is the expression in option A.
i.e.

which can be factored as follows:

.</span>
4(y - 7) = 2y - 38
4y - 28 = 2y - 38
4y - 2y = -38 + 28
2y = -10
y = -5
All you will have to do is put this inside of a graph and then see if it goes through the origin.
<span>ΔABC is not a right triangle.</span>
All you do is add them all together...
20 + 11.4 + 11.4 + 4.5 + 4.5 + 0.45 + 0.45 + 0.45 + 0.45 = 53.6Kg
(note that 0.45 is 450g in Kg, When adding things such as weight or length you want to make sure that they are all in the same unit)