Question

A picture is 5 inches wide and 8 inches tall:

Answer 1

250 just multiply the length and width by 2.5 and you get 12.5 and 20 then multiply those together and you get 250

Answer 2

To use a scale factor just means to simply multiply is by the number. If the scale factor is greater than one, the object gets bigger. If the scale factor is less than one, it gets smaller.
Since the scale factor in the problem is 2.5, the image is going to get bigger.
You multiply both 5 and 8 by 2.5, so 5*2.5= 12.5 and 8*2.5= 20.

So the final measurements will be 12.5 inches tall by 20 inches wide.

I hope that helps!