The following bar graph shows the number of accidents that happened in a city during the year 2021.

B = difference in accidents of two wheelers and buses. B is what percent of total number of accidents?

15%

According to the bar graph, 

Number of accidents in two wheelers = 330

Number of accidents in buses = 180

Their difference = 150

Total number of accidents in 2021 = 220 + 180 + 200 + 330 + 70

                                                  = 1000

Required percentage = $\frac{150}{1000}$ x 100 = 15%