1)One group of children want to buy a ball. If each of them would give 20$, not reach 40 $, but if each give 25$, it still remain 20 $. a) what is the ball's price b) how many kids are in the group.
2) If we place the students of a classroom 3 each in the desk, it will remain 3 empty desk, but if we place them 2 in the desk they 3 students will not have a place to sit. a) how many students are in the classroom b) how many desks are in the classroom?
3) If x+y = 2√2 and x*y=1 to demonstrate x2+y2