The weights of 4 boxes are 90, 40, 80 and 50 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?
Average age of 5 students of a school is 14 years. The average age of students and their Mathematics and science teachers is 30 years. If the age of science teacher is 6 years more than the age of Mathematics teacher, then what is the age (in years) of Mathematics teacher?