Anyone know how to solve this?

An airplane travels at an unknown elevation before it descends 3 miles to an elevation of 15 miles. find the elevation of the plane before its descen.

What's for breakfast? all people who ate at a certain restaurant were surveyed as to what they ordered on a particular sunday morning. 40 ate eggs 42 ate sausage 32 ate pancakes 13 ate sausage and eggs 15 ate pancakes and sausage 11 ate eggs and pancakes 6 ate all three items 3 people didn't eat any of the items how many people ate only pancakes? how many people ate at the resturant that morning? how many people didn't eat eggs?

The investigating team suspected that there were differences in the cost of repairing cars in workshop i and workshop ii. the investigating team suspected that the costs raised by workshop i were greater than workshop ii. for that they tested the repair of 15 cars in each workshop to see the cost of repairs.the decision of the right hypothesis to prove the suspicion above is a. h0 : μ1- μ2­ = 0; ha : μ1- μ2­ ≠ 0 b. h0 : μ1- μ2 ≥ 0; ha : μ1- μ2 < 0 c. h0 : μd ≥ 0; ha : μd < 0 with μd = μ2- μ1 d. h0 : μd = 0; ha : μd ≠ 0 with μd = μ2- μ1 e. h0 : μ1- μ2 = 0; ha : μ1- μ2 ≥ 0