The area of a rectangle is 56 square centimeters. the length of the rectangle is 8 centimeters, and the width is three less than a number. what is the number?

From the question, we know that:
a = 56
l = 8
w = n - 3

To find the number (n), we should find the width (w) first
General formula of rectangle area is
l × w = a

Input the number to the formula
l × w = a
8w = 56
w = 56/8
w = 7

After finding the width, we find n
w = n - 3
n - 3 = w
n - 3 = 7
n = 10

The number is 10