My super brain

1.) 99 if they are all pennies
2.) Take a piece of fruit from the box marked apples and oranges. Suppose the fruit you take is an apple. Then that box must be the box containing just apples. Therefore, the box marked oranges can't be the box containing just apples, and it can't be the box containing just oranges either  so it must be the box containing apples and oranges. The remaining box is therefore the box containing just oranges.
If the fruit you take out is an orange, the solution is derived in a similar fashion the box marked apples and oranges is the box containing just oranges the box marked apples is the box containing both apples and oranges and the box marked oranges is the one containing just apples.
3.) For 7 gallons, fill the 5 gallon jug and dump what you can into the 3 gallon jug, filling it. There are now 2 gallons in the 5 gallon jug. Dump out the 3 gallon jug, and put the 2 gallons from the 5 gallon jug into the 3 gallon jug. Then fill the 5 gallon jug. The total is 7 gallons.
4.) July
5.) 3
6.) 28
7.) Ask one robot what the other robot would say, if it was asked which door was safe. Then go through the other door.