In a mall that sells skirts, 42 black skirts were sold and 25% of the remaining skirts that were sold were blue. Of the leftover, 50% of the skirts sold were purple skirts and the rest were brown skirts. Given that the number of brown skirts sold was 20% of the total number of skirts sold, how many blue and black skirts were sold altogether?
25% = ²⁵₁₀₀ = ¹₄
50% = ⁵⁰₁₀₀ = ¹₂
20% = ²⁰₁₀₀ = ¹₅

Black	Blue	Purple	Brown
42	1x2	3x2
		1x3	1x3
4x3			1x3
7 u	2 u	3 u	3 u

The total number of purple and brown shirts is the combined repeated identity. Make the total number of purple and brown shirts the same. LCM of 3 and 2 is 6.

The number of brown shirts is repeated. Make the number of brown shirts the same. LCM of 3 and 1 is 3.

Number of black skirts
= 12 u - 2 u - 3 u
= 7 u

7 u = 42

1 u = 42 ÷ 7 = 6

Number of blue and black skirts
= 2 u + 42
= (2 x 6) + 42
= 12 + 42
= 54

Answer(s): 54