Because A= 10 B=8, (3A-B)=22 people.
Half of the people get off the bus halfway, so 22*0.5= 1 1 person.
So there are 1 1 people left in the car.
(8A-5B)=40 people (there are * * * people after getting on the bus)
40- 1 1=29 people (boarding number)
the second question
Is there something wrong with your question ~ Is it the result of A-XY-2YZ+3SZ or the correct result of A-(XY-2YZ+3XZ)?
Because a-xy-2yz+3sz+(xy-2yz+2xz) = 2xy-3xy+2yz.
a-XY-2YZ+3SZ = 2XY-3XY+2YZ-(XY-2YZ+2XZ)
a-XY-2YZ+3SZ = 2XY-3XY+2YZ-XY+2YZ-2XZ
=4YZ-2XY-2XZ