Answer 1

https://code.sololearn.com/cF9FTszTBkre/?ref=app
1)All variables that used in external classes must be public
2)In line 17 => b1.b1 you must chenche to b1.bal
3)In line 20 => you can't substract double and integer you must have variable of common type
4)Class WithDraw don't have void wDraw
5)Take this code, maybe i forgot anything.