Math homework
So... We got a homework for bonus points so I can't figure out what to do.
Some passangers enter the bus at the beginning. At the first stop 1/9 of those passangers step out. At second stop no one steps out, but the number of passangers is increased by 3/4 of the number of how many came there anyway. At the third stop, 6/7 of passangers who arrived step out and there are 16 passangers left.
How many passangers entered the bus at the beginning?
I know the answer is 72, don't know how to get it.
Tried: z-1/9z+3/4z-6/7z=16 and z-1/9z+3/4x(z-1/9z)-6/7x(3/4x(z-1/9z)=16
Doesn't work out. FFFUUUUU
I don't even know from where the z's showed up .