150 miles in 6 gallons to the nearest hundredth

If 20% of a number is 35, what is 50% of that number?

Hi my sisters and brothers can tell me the answer because i don’t understand the question

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.