You are correct. My apologies for the error. Let's re-solve 4. a) with division.
4. a)
Step 1: Rewrite the division of fractions as multiplication by the reciprocal of the second fraction.
53÷712=53×127
Step 2: Multiply the numerators and multiply the denominators.
5×123×7=6021
Step 3: Simplify the fraction by dividing both the numerator and the denominator by their greatest common divisor.
The greatest common divisor of 21 and 60 is 3.
60÷321÷3=207
The simplified expression is 207.