1 3 - + - 4 5

It seems you're trying to add two fractions. To add fractions, you need to find a common denominator, which is a common multiple of the two denominators you have. In this case, the denominators are 4 and 5.

The least common denominator (LCD) for 4 and 5 is 20 because 20 is the smallest number that both 4 and 5 can divide into without leaving a remainder.

Here's how you can add the fractions step by step:

1. Convert each fraction to an equivalent fraction with the common denominator of 20:

1/4 becomes 5/20 (because 1 × 5 = 5 and 4 × 5 = 20) 3/5 becomes 12/20 (because 3 × 4 = 12 and 5 × 4 = 20)

2. Now that the fractions have the same denominator, you can add them:

5/20 + 12/20 = (5 + 12)/20 5/20 + 12/20 = 17/20

The sum of the fractions 1/4 and 3/5 is 17/20.