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Home > MC2 > Chapter 9 > Lesson 9.1.2 > Problem 9-21


Joaquin has agreed to lend his younger brother so that he can buy a new tank for his pet lizard. Joaquin is charging his brother simple interest per month. If his brother pays him back in months, how much will Joaquin get back?

Using the equation for simple interest:

r interest rate

Interest ()( months)

Remember, the total money Joaquin gets back includes the principal and the interest.