The weights of 4 boxes are 30, 40, 50 and 100 kilograms. Which of the following cannot be the total weight, in kilograms, of any combination of these boxes and in a combination a box can be used only once?
A street vendor pushes his cart 2 km South, then he turns East and walks 2.5 km, then he turns North and walks 1 km, then he turns to his left and walks 2.5 km. Where is he with respect to his starting point?