Explanation

To evaluate the expression 7/12 - 3/8 - 4/9:

Step 1: Find the least common multiple (LCM) of 12, 8, and 9.

The LCM of 12, 8, and 9 is 72.

Step 2: Convert each fraction to have a denominator of 72.

7/12 = (7 × 6) / (12 × 6) = 42/72

3/8 = (3 × 9) / (8 × 9) = 27/72

4/9 = (4 × 8) / (9 × 8) = 32/72

Step 3: Subtract the fractions.

42/72 - 27/72 - 32/72 = (42 - 27 - 32) / 72

= (42 - 59) / 72

= -17/72