Could you me with all of the questions

Find the least common multiple of the expressions: 1. 3x^2, 6x - 18 2. 5x, 5x(x +2) 3. x^2 - 9, x + 3 4. x^2 - 3x - 10, x + 2 explain if possible

Alistair has 5 half-pounds chocalate bars. it takes 1 1/2 pounds of chocalate,broken into chunks, to make a batch of cookies. how many batches can alistair mke with chocalate he has on his hand?

Me because i don't understand how to do it.: )