Which of the following equations must also be true?

a + d = b + c

Step-by-step explanation:

a + c = a + b => a + c = 2a (wrong)

a + d = b + c => a + c = a + c (right)

a - c = d - b => a - c = c - a (wrong)

ad = cd => ac = (wrong)

the answer to your question a or b but i am pretty sure it is b. i hope this : )

step-by-step explanation:

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