Find the rate at which N280 will earn N21.00 psimple interest for 2 and the half years

Not sure about my calculations Mr jiskha

21*5=105 divided by
2 =5.25 %
{% because we were given principal and time}

I = Prt, so

280 * r * 2.5 = 21
r = 0.03 = 3%