The following image was made by Subtract Fractions with Circles Designer:

When the program starts, you will be asked to identify the minuend in the first row and then the subtrahend in the second row. The program will continue when the minuend and subtrahend are correctly identified. You will then be asked to find the difference.

The difference must be entered as a mixed or whole number in lowest terms.

You can see from the picture that the minuend is 3 2/3 units and the subtrahend is 2 1/2 units. The difference is what is left after removing the blue circles in the second row from the red circles in the first row. In many examples, you can arrive at the difference by looking at the picture. For example, after removing the two whole circles, you are left with 1 2/3 red circles. Removing the 1/2 circle from the 1 2/3 circle that is left in the minuend will leave 1/2 + 2/3 circle for the difference of 1 1/6 circles.

You may prefer to work vertically:

The program SUBTRACT FRACTIONS shows how to subtract fractions with circles.

The program RENAME TO LOWEST TERMS shows how to write fractions in lowest terms

The program IDENTIFY MIXED NUMBERS shows how to write fractions as a mixed number.