michael_wind

Category none "sunroof only" "anti-theft only" "both sunroof and anti-theft"
                 75            a                      b                               40                 

Then, those with sunroof = a + 40; those with anti-theft = b + 40
Since 有sunproof的车的数量是有报警装置的车的数量的2倍, then a + 40 = 2 * (b + 40)
In addition, the total # of cars = 200 = 75 + a + b + 40

With these two equations, you can get what a and b should be.