what is prime factorization and how do I solve this question???

Answer:
rime factorization or integer factorization of a number is breaking a number down into the set of prime numbers which multiply together to result in the original number Step-by-step explanation:
so for that you do 3 x 7 which is 21 x 2= which is 42 and on the the other right side you write 2 and the bottom you just write 2 please mark brainliest