In case A, 15 of the 200 patients are chosen; and they are 5 of the 40 cardiac patients and 10 of the 100 cancer patients. The probability is
(40 choose 5)*(100 choose 10)
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200 choose 15
Use a calculator and express the result in the desired/required form.
Case B is similar; the probability is
(40 choose 2)*(100 choose 5)*(60 choose 4)
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200 choose 11