Whats the percent change from 100 to 140

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

Alicia puts $400 in a bank account. each year the account earns 5% simple interest. how much money will be in her bank account in six months?

Two corresponding sides of two similar triangles are 3cm and 5cm. the area of the first triangle is 12cm^2. what is the area of the second triangle?