Did you mean find the simple interest?
If so... here is the method to use.
Interest = Principle x Rate x time
P = 2400
R = 10.5% use .105 in the formula
T = 1.5
Find the simple rate
Principal $2400
Rate 10 1/2%
Time in years 1 1/2
3 answers
Yes Meant interest
Then you just have to multiply 2400 x .105 x 1.5