2b^2 + 81/2 b + 4
basically 2b^2 + 16b + 49/2 b + 4
= (2b^2) + 16b+49/2b) + (4)
= 2b^2 + 81/2 b + 4
So the equation for a trapezoid is

, with the b variable being the 2 bases, h variable for height, and the a variable for area. Firstly, we will need to plug in the appropriate numbers into the equation, and it'll look like this:

Next, we will need to combine 12 and 14, then divide the sum by 2. Your equation should look like this:

Lastly, just divide each side by 13, and your answer should be
7) So when x=6 then z=72, they are directly proportional, so if I multiply the first with a number, then I have to multiply the second with the same number.
6 becomes 13 (x) /multiplied with about 2.167/
72 becomes 156(y) /multiplied with about 2.167/
8) Inversely proportional, so if I multiply the first with a number, then I have to divide the second with the same number.
6 becomes 13 (x)
2 becomes ~0.92307(y) /round it to the thousandths place and you get 0.923/
Those are called "even numbers".
Also, I guess, "multiples of 2" .