The following histogram shows the monthly income range of families staying in an apartment.

What is the difference between the total number of families whose income is more than or equal to 10000 but less than or equal to 25000 and the total number of families whose income is more than 35000 but less than or equal to 50000?

4

Number of students b/w 10000 and 25000 = 3 + 4 + 8 = 15

Number of students b/w 35000 and 50000 = 10 + 4 + 5 = 19

Required difference = 19  - 15 = 4