The formula for the area of a trapezold with altitude k and bases m and n is A=k/2(m+n)
Solve for m.

Answer:
[tex]m=\frac{2A-kn}{k}[/tex]
Hence, option C is true.
Step-by-step explanation:
Given the expression
[tex]A=\frac{k}{2}\left(m+n\right)[/tex]
Solving for 'm'
[tex]A=\frac{k}{2}\left(m+n\right)[/tex]
Flip the equation
[tex]\frac{k}{2}\left(m+n\right)=A[/tex]
Expanding by applying the distributive law: [tex]a\left(b+c\right)=ab+ac[/tex]
[tex]\frac{1}{2}km+\frac{1}{2}kn=A[/tex]
Add (-1)/2 × kn to both sides
[tex]\frac{1}{2}km+\frac{1}{2}kn+\left(-\frac{1}{2}kn\right)=\left(-\frac{1}{2}kn\right)+A[/tex]
simplify
[tex]\frac{1}{2}km=-\frac{1}{2}kn+A[/tex]
Divide both sides by k/2
[tex]\frac{\frac{1}{2}km}{\frac{k}{2}}=\frac{-\frac{1}{2}kn+A}{\frac{k}{2}}[/tex]
[tex]m=\frac{2A-kn}{k}[/tex]
Therefore,
[tex]m=\frac{2A-kn}{k}[/tex]
Hence, option C is true.