Pls me asal for all (show work for ! ) + lots of points *marking it smartest*

First one I'm not sure the second one or number 4 you do 50 times 30 then divide by 100 to see what the sales price is. which is 35$, the third one or number 3 you use the options below to get your answer. the answer would be 44because it divided by 2 = 22 minus 10 = 12 the fourth or number 5 all you have to do is divide 180 by 42 which is 4.28 rounded to 4 buses. the fifth or number 3 in this you would use the options below and divide by 52 to try and get three which is the final option 156. for the sixth or number 6 is C. 

Hope I helped

1. subtract 31 - 18.5= 12.5 then divide by 2 and get 6.25
2. 12 times 2 then add 10 giving you 32
3. 52 divided by 2 then multiply by 3 and you get 78
4. D 
5. multiply 5 by 42 and you get 210 which is the least amount of buses
6. C
Sorry not good with discounts but the rest is good