please help with both parts of this question

12. Two old payments on a debt were arranged. The first payment for \\( \\$ 1.200 \\) was due in 6 months, paying \11.5, compounded quarterly; the second payment of \\( \\$ 600 \\) was due in 12 months, paying \12, compounded monthly. These are to be replaced by two equal payments due in 9 and 18 months, respectively. What is the size of these payments if money is worth \13, compounded semi-annually? Use 9 months from now as the focal date. (10 marks) Preliminaries: Diagram