Question

Leonardo da VInci's famous painting the Mona Lisa measures 77.5cm by 55cm. What dimensions would make a a postcard similar to the original painting. Approximate to the nearest tenth. Show your work or explain how you found your answer.

Answer 1

So what similar means is that even though your new picture will be smaller, both sides will be smaller and they will still be the same ratio. For example, if the picture I was shrinking had a width that was half as long as the height, then for the new picture, it would still be half as long even though both are shorter.

Answer 2

So the easiest way to write this algebraically is this:
if A is your new height and B is your new width, then
77.5/55 = A/B

It seems like you can pretty much pick any A that makes sense as the height of a postcard or any B that makes sense as the width of a postcard, then solve for the other variable.