You invest $3000 in an account that pays simple interest of 7% for 30 years. how much will you have at the end of 30 years?

$9,300
First, multiply your beginning amount by the percent of interest: 3,000x0.07 = 210
Then, multiply your interest times the number of years:
210x30 = 6,300
Add you interest to your initial amount:
3,000 + 6,300 = 9,300