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Omar can have his double scoop either mixed (two flavors) or unmixed (one flavor)
there are 4 flavors, so there are 4 unmixed combinations
each of the four flavors can be combined with three other flavors, for a total of 4*3 or 12 mixed combinations
BUT . . . half of the mixed combinations are duplicates -- vanilla & raspberry is the same as raspberry & vanilla
. . . so there are really only 6 mixed combinations
4 unmixed and 6 mixed gives a total of 10 possible combinations