Aboy can raise a rock that weighs 95n by using a lever and applying force of 15n what is the mechanical advantage of the lever

The mechanical advantage is 6.33

Explanation:  Mechanical advantage is calculated as:

Ma = Fb/Fa where Fb is the force that the machine does, and Fa is the force that you do to the machine.

The minimal force needed to lift an object is equal to its weight, so here the force that does the machine, Fb, is equal to 95N.

And we know that the force that the boy does is equal to Fa = 15N, so using the equation for the mechanical advantage we have:

Ma = Fb/Fa = 95N/15N = 6.33