Robert bought a hard drive for 30% off the regular price. The sale price was $42.00. What was the regular price?

Regular price will be $54.6

Step-by-step explanation:

30/100× $42 = 12.6

Then add the $12.6 to the sales price of $42

You get the regular price

option a is correct.

step-by-step explanation:

scale factor: it is used to find proportional measurements.

proportions means having the same ratio.

scale factor is the ratio of the model measurement to the actual measurement in a simplest form.

or we can say that the ratio of any two corresponding lengths in two similar geometric figures

if the scale factor is more than 1, then it is an enlargement,

if the scale factor less than 1, then it is a reduction.

given the two geometric figure:

by definition of proportions, we have