Revenue measurement – settlement discounts with change in estimate

A ltd sales of CU 100,000 on 31,Dec,2014, all of which were on credit
On 31 Dec 2014, it is expected that 60% of these debtors will settle early and qualify for a 10% settlement discount (i.e. settled within 30 days)
During January 2015, 40% of the debtors actually settle within 30 days and not the 60% expected. The remaining 60% debtors settle during Feb 2015.
Assume that time value of money effects is immaterial and ignore VAT

Required:
a. Calculate the revenue recorded in Dec in P/L
b. Journalise the complete transaction