Note also:
1) Earn is per USD.
2) Normal earn is 2 KF miles/USD or ~1.5 KF miles/SGD depending on exchange rate
3) 5 KF miles/USD is earned the promotion period, from Jun 14th, 2019 to Sep 30th, 2019. This is ~ 3.5 KF miles/SGD
4) Must be booked through link:
https://www.easyrentcars.com/partners/singaporeairlines