Pam and Jim are saving money for their two children who they plan to send to university.

The eldest child will enter university in $5$ years while the younger will enter in $7.$ Each child is expected spend four years at university. University fees are currently R$20000$ per year and are expected to grow at $5\%$ per year. These fees are paid at the beginning of each year.

Pam and Jim currently have R$40000$ in their savings and their plan is to save a fixed amount each year for the next $5$ years. The first deposit taking place at the end of the current year and the last deposit at the date the first university fees are paid.

Pam and Jim expect to earn $10\%$ per year on their investments.

What amount should they invest each year to meet the cost of their children$$s university fees?