The simple interest formula is A = P (1 + r) t where P represents the amount originally deposited, r is the interest rate, and A is the amount in the account after t years.

Find r if A = 2700, P = 2200 and t = 5.

2700 = 2200 (1 + r) 5

Express r as a percentage to one decimal place (x. x%).

To find this, you just need to plug it in and use some algebra to figure it out.

Initial: 2700 = 2200 (1 + r) 5

multiply 2200 and 5: 2700 = 11000 (1 + r)

Divide both sides by 11000:.24 = 1 + r

subtract both sides by 1: -.754 = r

The problem is, a negative interest rate makes no sense if there was actually an increase of 500. We can try distributing the 11000 instead

Where we left off: 2700 = 11000 (1 + r)

Distribute the 11000: 2700 = 11000 + 11000r

Subtract 11000 from both sides: - 8300 = 11000r

Divide both sides by 11000: -.754 = r

As you can see, both methods reached the same impossible answer. I'm assuming that you didn't type out the equation right. Are you sure it wasn't

2700 = 2200 (1 - r) 5

? If you subtract the r to make it negative, it might make more sense. But that still leaves us with a. 754 rate of interest, which seems too high. Double check where you're typing from