What shows a difference of squares?

You eat 8 strawberries and your friend eats 12 strawberries from a bowl. there are 20 strawberries left. which equation and solution give the original number of strawberries?

One of the same side angles of two parallel lines is 20° smaller than the other one. find the measures of these two angles.

What function has a range {yly< 5}? question on picture above^