Ratios shall be used
Selling 3x as many tie-dyed as silk is the equivalent of ratio 3:1 (Three tie dies for 1 silk)
Add up the total numbers in the ratio (By that I mean 3 + 1) to get 4
Divide the total number sold by 4 to get 42
Multiply 42 by 3 (The number of tie dyes sold in the ratio) to get 126
126 tie-dyed shirts were sold