If the feed per revolution on an upright drilling machine is set to 1/64" and the rpm is set to 105, how many revolutions are required for the drill to advance 2 1/8" into the part?

Proportion states that the two ratios or fractions are equal.

As per the given statement:

f the feed per revolution on an upright drilling machine is set to 1/64" and the rpm is set to 105.

Let x represents the revolutions are required  for the drill to advance into the part.

By definition of proportion:

By cross multiply we have;

Multiply both sides by 64 we get;

Simplify:

Therefore, 14,280 rpm revolutions are required for the drill to advance into the part

not sure but it may be b, as i said i'm not sure.