Answer: 11/13
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Step-by-step explanation:
Add up the four numbers given: 4+8+4+10 = 26 items total
Kick out the 4 black shirts since they are neither blue, nor are they pants.
So we have 26-4 = 22 items that are blue or a pair of pants (or both).
Divide that over the total (26) to get the probability we're after:
22/26 = (11*2)/(13*2) = 11/13
Side note: 11/13 = 0.8462 = 84.62% approximately