B. triangle ABC is isosceles. The angles add up 180 degrees.
20,000,000+400,000+80,000+4,000+100+60+3
Step-by-step explanation:

- In the line 2, only variables were operated with a reduction of similar terms in each side of the equation, giving as result -4x at one side, and 2x at the other side.
- In the line 3, terms with variables were joined together in one side of the equation, and then, they were operate it, given as result -6X.
To find the value of C: Use the Pythagorean Theorem
4^2 + 3^2 = c^2
16 + 9 = c^2
25 = c^2
sqrt of 25 = c
c = 5