At a local fitness​ center, members pay a ​$6 membership fee and ​$3 for each aerobics class. Nonmembers pay ​$5 for each aerobics class. For what number of aerobics classes will the cost for members and nonmembers be the​ same?

Let's assume the number of aerobics classes as x.

For members, the total cost would be $6 (membership fee) + $3 (cost per class) * x (number of classes).
For nonmembers, the total cost would be $5 (cost per class) * x (number of classes).

Setting the two costs equal, we get:
$6 + $3x = $5x

Simplifying the equation, we get:
$6 = $2x

Dividing both sides by $2, we get:
3 = x

Therefore, for 3 aerobics classes, the cost for members and nonmembers will be the same.