The general formula for the sides of right triangle is
a² + b² = c²
Subtitute the equation of a and b to the formula a² + b², evaluate if the answer will be the same as the equation of c²
a² + b²
= (m² - n²)² + (2mn)²
= (m² - n²)(m² - n²) + (2mn)(2mn)
= (m⁴ - 2m²n² + n⁴) + 4m²n²
= m⁴ + 2m²n² + n⁴
Factorize the result
m⁴ + 2m²n² + n⁴
= (m² + n²)(m² + n²)
= (m² + n²)²
= c²
It's proven by the formula that c² = (m² + n²)²
so the c will be m² + n²
I think it would 66.6% or 67%
18+9 is 27
18/27 is 2/3 which is basically 66.6% repeating
Distribute the -1/2 to both x and 12
-1/2(x) = -1/2x
-1/2(12) = -6
12 - (-1/2x) - 6
Simplify: Note, two negatives = one positive
12 + 1/2x - 6
Simplify: combine common numbers together
12 - 6 + 1/2x
6 + 1/2x
1/2x + 6 is your equivalent expression
hope this helps