Physics exam questions help? Unit 2? :-)

HI, im stuck on these two questions:
1. calculate the current drawn from the mains electricity supply by the drill. I got given that the power supply is 230 V,power input is 1012W and that the mass is 6kg so what equation do i use?
2. Technetium-99 us used by the doctors as a medical tracer. In hospitals, it is produced inside a technetium generator by the decay of a molybdenum-99 nuclei.
Figure 7 shows how the number of nuclei in a sample of molybdenum-99 changes with time as the nuclei decay.

A technetium generator will continue to produce sufficient technetium-99 until 80 percent of the original molybdenum nuclei have decayed.
After how many days will a source of molybdenum-99 inside a technetium-99 generator need replacing?
Number of days = ...........