when you name a plane using 3 letters does the order of the letters matter

No, the order does not matter.

Sometimes, depending on the question being asked there can be an order that is easier to use (for example if the plane is represented in a drawing it can sometimes be nice to name the points from left to right or top to bottom as they appear in the drawing, or you might like to name the points alphabetically) but this is NOT required and is not "more correct" than any other order.

Answer for 2: his profit would be $2.88 explanation: you have to first multiply 72 and 0.12 together to get $8.64 once you do that you know how much money the shopkeeper made from selling the candy bars individually. so you have to do 8.64-5.76=2.88 hope that ; )answer for 3: yeah i’m sorry i have no idea what number 3 is. i’m sorry i couldn’t with that.