Mya was given the following reduction of a rectangle.

A rectangle has a length of B and width of 10 feet. A smaller rectangle has a length of 8 feet and width of 4 feet.

Mya calculated the scale factor to be One-half. What error, if any, could Mya have made when she calculated the scale factor?
Mya only used the dimensions from the scale drawing of a rectangle.
Mya used the 10 ft side and the 8 ft side as corresponding sides.
Mya divided the dimensions, instead of multiplying them, to find the scale factor.
Mya did not make an error when she calculated the scale factor.