How to determine skeins of yarn needed for a project

I have a easy crochet pattern but the materials portion is complicated.
(100% acrylic; 6oz/170g, 315yds/288m):
18 (24,24,30,30) oz (A)

(100% acrylic; 3oz/85g, approx 150yds/137m ball):
9 (9,12,12,12) oz (B)

Can someone help me figure out how much yarn I need for this project? There are 5 sizes. S (M,L, 1X,2X) I need yarn for size M.
Thanks in advance

Forums: 

For color A, which is listed as 6 oz skeins, you would need 3, 4 or 5 skeins (dividing the number of ounces per skein into the number of ounces required). The same figuring is required for color B, dividing the 3 oz skein into the 9 or more ounces required. Hope this is helpful!

Merry Christmas! Marian