Answer:12 black,6 black, 3 black, 4 black, 1 red
Explanation:
black are positive numbers and red are negative and we have to get positive 24 if he uses 12 black he would have a product of positive 12 the adding 6 black, 4 black and 3 black then he would have a total product of 25 and using the 1 red card it would minus 1 giving him a product of 24