A manufacturing plant makes two types of inflatable boats, a two-person boat and a fourperson boat. Each two-person boat requires 0.9 labour hours from the cutting department and 0.8 labour hours from the assembly department. Each four-person boat requires 1.8 labour hours from the cutting department and 1.2 labour hours from the assembly department. The maximum labour hours available per month in the cutting department and the assembly department are 864 and 672 respectively. The company makes a profit of E25 on each twoperson boat and E40 on each four-person boat. Use the graphical method to find the maximum profit.