Answer:
for 30 its Prime factorization of 30 = 2 × 3 × 5. Using all prime numbers found as often as each occurs most often we take 2 × 2 × 3 × 5 = 60. Therefore LCM (12,30) = 60.
for 42 its 42 and 54 is 378.
for 54 its The prime factorization of 54 is: 2 x 3 x 3 x 3. The prime factorization of 72 is: 2 x 2 x 2 x 3 x 3. Eliminate the duplicate factors of the two lists, then multiply them once with the remaining factors of the lists to get lcm(54,54) = 2
Explanation: