Find answer for A and B

Factorize: x^2+8x+10 i just solved it but i don't know if the process is correct

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

Diane’s bank is offering 5% interest, compounded monthly. if diane invests $10,500 and wants $20,000 when she withdrawals, how long should she keep her money in for? round to the nearest tenth of a year.