How do i solve this?

1.-4

2.7

3.-11

4.18

5.13

Step-by-step explanation:

0-4=-4

-2+9=7

-2-9=-11

5+13=18

-10+23=13

from the figure we get,

the x axis shows   the months and,

the y-axis shows the number of satisfied customer.

each line or each cell in upward direction (y-axis) shows 500.

the appropriate scale for the y - axis is: -

a = 2000 customers

b = 4000 customers

c = 6000 customers

d = 8000 customers

e = 10000 customers

f = 12000 customers

g = 14000 customers