It's the third answer. This is because since there is no middle term where both variables are combined, that would lead to the signs of the 2 factors to be different. However, that still leaves 2 answers, 3 and 2. If we were to square i, you would get -1. This is because √-1 is equal to i. i^2 would be -1. Since the sign in the unfactored expression is positive and not negative, that would mean that the i in the factoring turned it around. that leads us to believe that answer 3 is the correct answer.
I'm pretty sure you're supposed to use Pythagorean Theorem, so here goes:
a^2+b^2=c^2
=8^2+b^2=10^2
=64+b^2=100
=b^2=100-64
=b^2=36
=b=6
So, AD=6
Then, 6*2=12
AC=12cm
All value less than -6 make that inequality true
In order to find 30% of 75, we simply calculate 75 x 0.3.
75 x 0.3 amounts to 22.5, which is the amount we deduct.
This leaves a final price of $52.50.