How does estimating an addition or subtraction problem help you know if ananswer is reasonable?

Question 5 spring semester final exam math evaluate

The owner of the plant nursery where you were tells you to fill 350 ml bottles from a 30 l from a fertilizer

Onnie is considering doing some long term investing with money that she inherited. she would like to have $50,000 at the end of 30 years. approximately how much money would lonnie need to put into an account earning 6% interest compounded annually in order to meet her goal?