1/3 of a cup = 3/9 of a cup. If you have 7/9 of a cup, the most 3/9ths that can fit in it is two 3/9ths, which equals 6/9. 6/9 < 7/9. Another latte would give you 9/9, and 9/9 > 7/9 so that's not possible. So two lattes can be made with 7/9 cups of milk.
Part A: In order to make an equation without a solution, all you need to do is this:


This makes the equation impossible, as no number equals itself plus two.
Part B: This is easier. Literally every random equation should work.


Now, use substitution:

x = 2
The altitude of the right triangle is the geometric mean of the 2 parts of the side it separates.
a. The answer would be sqrt(18*32)=24
The question to the second question can be answered by using the Pythagorean theorem.
32^2+24^2=1600=40^2
b. The answer would be sqrt40^2=40