The following  image was made from Add with Lines Designer:

Add Unlike Image showing number lnes

You will notice that the addends 1/5 and 1/2 have unlike denominators. You must first rename 1/5 and 1/2 with a like or common denominator(LCD).  The program COMPARE FRACTIONS shows how to find the LCD. In this case, each addend is written with a common denominator 10.

Once each addend is written with like denominators, the numerators may be added for the sum numerator.

The program ADD FRACTIONS - EASY shows how to add fractions with like denominators.

See an animation of number-line addition. The animation was made with the Fraction Designer series.