To solve for a variable, you have to isolate that variable onto one side.
1.
Firstly, multiply both sides by 2: [tex]2A=(a+b)h[/tex]
Next, divide both sides by a + b and your answer will be: [tex]\frac{2A}{a+b}=h[/tex]
2.
For this, divide both sides by πr², and your answer will be [tex]\frac{V}{\pi r^2}=h[/tex]
3.
Firstly, subtract both sides by 2πr²: [tex]SA-2\pi r^2=2\pi rh[/tex]
Lastly, divide both sides by 2πr, and your answer will be: [tex]\frac{SA-2\pi r^2}{2\pi r}=h[/tex]
