There are two c's. You must pay attention to capitalization, there's a lowercase c and an uppercase C which represent two different variables. Also, the W is capitalized which could make your answer incorrect if you don't use the same notation.
Solving for small c..

So it's the answer shown in the picture, but it should be a capital W instead of a lowercase w.
For part A, turn 10x + 5y = 20 into slope intercept form. An equation with the same slope as Amanda’s equation will be linear. I hope this helps :)
18^2 + 68^2 =
= 324 + 4,624
= 4,948
74^2 = 5,476
4,848 is not equal to 5,476.
Since the sum of the squares of the lengths of the two shorter sides is not equal to the square of the length of the longest side, the triangle is not a right triangle.