To subtract a whole number by a fraction, let's first transform the whole number into a fraction with the same denominator as the fraction to be subtracted.
Given: 4 - 9/7
Step 1: Converting 4 into a fraction with the denominator of 7.
Step 2: Let's now proceed with the subtraction.
Step 3: Let's convert 19/7 into a mixed number.
Therefore, the answer is 19/7 or 2 5/7.