Can you please show how to do this question by using formula.

Thank you.

Jacqueline had to make a payment of $2,400 in 11 months and $2,000 in 19 months, to a raw material supplier. What single payment in 4 months would settle both these payments? Assume a simple interest rate of 4.50% p.a. and use 4 months from now as the focal date. $4,224.50 Round to the nearest cent