Mary worked from Monday to Saturday last week and bought lunch in the company’s restaurant every day.
Her lunches cost a different amount every day.
Each lunch cost a multiple of 20¢.
The most expensive lunch of the week cost $7.60 and the cheapest one cost $4.40.
Friday’s lunch cost exactly 11⁄2 times as much as Wednesday’s lunch.
Tuesday’s lunch cost $1.20 more than Thursday’s lunch.
(a) What is the minimum total that Mary’s six lunches last week could have cost?
(b) What is the maximum total that Mary’s six lunches last week could have cost?