Can you help me with a forumula for this question

A friend wants to retire in 30 years when he is 65. At age 35, he can invest

$200/month that earns 5% each year. But he is thinking of waiting 15 years when he is age 50,

and then investing $500/month to catch up, earning the same 5% per year. He feels that by

investing over twice as much for half as many years (15 instead of 30 years) he will have more.

What is the future value of each of these options at age 65, and under which scenario would he

accumulate more money?