Medium
Common factor of 10pq, 20qr, 30rp is -
Explanation
Explanation
Look at the numeric coefficients first: 10, 20, and 30 all share a common factor of 10. Now check the variables: 'p' appears in the 1st and 3rd terms but not the 2nd; 'q' appears in the 1st and 2nd but not the 3rd; 'r' appears in the 2nd and 3rd but not the 1st. Since no single variable is common to all three terms, the overall common factor is simply the number 10. So the correct answer is 10, option (3).
PRO TIP
Re-check your working by substituting the answer back into the original question.