Please help with Q3 (Jerome) & 4 (Tetra) of June 2012

These problems might be very easy for you, hope you can help.
Many thanks!

Q3 Jerome
(b) Taxable benefits in respect of private use of the motor car.
I dont understand where is the 27% come from. Why is it 15% + (170-125) / 5 +3% ?
What is 15% and 3%? and why is it divided by 5?

Q4 Tetra
(c) It says “Tetra’s net income would exceed 100,000 + 2 X 7450, what is this criteria for?

Thanks very much!