A cone resting on its base, with a dashed line from the side of the circle to the center of the circle labeled r. The edge of the cone is labeled Slant height (l).
The surface area of a cone is given by the formula
S = πl + πr2. Solve the formula for l.

l = S – r2
l = S + r2
l = l equals StartFraction S Over pi minus r squared. – r2
l = l equals StartFraction S Over pi plus r squared. + r2

Question

A cone resting on its base, with a dashed line from the side of the circle to the center of the circle labeled r. The edge of the cone is labeled Slant height (l). 
The surface area of a cone is given by the formula
S = πl + πr2. Solve the formula for l.

l = S – r2
l = S + r2
l = l equals StartFraction S Over pi minus r squared. – r2
l = l equals StartFraction S Over pi plus r squared. + r2

Mercury · Answer

it asks to solve S = πl + πr2 for l

remember, to solve for a variable, think about what is being done to the variable, and do the opposite, keeping order of operations in mind

so, to start, subtract pi r^2 from both sides, which will leave you with pi* l alone on the right side. from there, divide both sides from pi to isolate l.