The hourly rate for work at the supermarket is $10 for 8 hours a day. If a worker works for more than 40 hours a week, the hourly pay is increased by 25% and it is further increased by 50% of the base rate for hours worked in excess of 60 per week.

Jane worked 12 hours a day for 6 days of the week. The total number of hours that she worked for is 12*6 = 72. For 40 hours of her work she is paid 10*40 = 400; for the next 20 hours she is paid 12% more than the base rate, this is 1.25*10*20 =  250 and for the rest she is paid 50% greater than the base rate or 10*1.5*12 = 180

The total amount earned by Jane in the week is $830.