David W. answered • 02/08/15

I'll help you understand math!

Giulia, this is a ratio problem. First, we can write the dimensions of the print 14/20. This can be reduced, of course, to 7/10.

If w = the width of the postcard, then 7/10 = w/6. The widths are the numerators and the lengths are the denominators.

Cross multiply, and we get 10w = 42, so w = 4.2 inches.

Let's check. The postcard is 4.2 x 6, compared to the 14 x 20 print. 14 ÷ 4.2 = 3 1/3 and 20 ÷ 6 = 3 1/3. Check.

Hope this helps!