Question

Amy painting copy has dimensions 2 inches by 1.5 inches. The scale of the copy is 1 in:40 cm. What the dimensions and area of the the original painting. Please explain!

Answer 1

units are just like fractions; they can be cancelled
multiply 2 in and 1.5 in by (40cm/1 in) to convert it from inches to centimeters (notice how the inches in the numerator and denominator cancel), because the ratio is 40 cm:1 in.
the original painting is 80 cm by 60 cm, so its area is 4800 cm^2.