Find a pair of factors for each number by using the difference of two squares.
a. 45
b. 77
c. 112

The answers are:
a) 9 and 5
b) 11 and 7
c) 14 and 8

a² - b² = (a + b)(a - b)

a) The answer is 9 and 5

45= a² - b²
45 = 49 - 4 = 7² - 2² = (7 + 2)(7 - 2) = 9 * 5

b) The answer is 11 and 7

77 = a² - b²
77 = 81 - 4 = 9² - 2² = (9 + 2)(9 - 2) = 11 * 7

c) The answer is 14 and 8

112 = a² - b²
112 = 121 - 9 = 11² - 3² = (11 + 3)(11 - 3) = 14 * 8

First find out how many gray T-shirts there are and how many black T-shirts.

Add up the numbers in the Black column, you get 20.
Add up the numbers in the Gray column, you get 14.

Ratio of the number of gray T-shirts TO the number of black T-shirts.

The keyword here is 'to', because this is what divides the two ratios. Number of gray T-shirts is 14, and the number of black T-shirts is 20, so we have:



We can simplify this by dividing 2 to both numbers: