A player holds 13 cards of four suits, of which seven are black and six are red. There are twice as many diamonds as spades and twice as many hearts as diamonds. How many clubs does he hold ?	Choices.
A) 4 B) 5 C) 6 D) 7 E) 8
D=2S   H=2D =4S   6+S+2S+4S=13;6+7S=13   2S+4S=6S 2 +4= 
<gadget id="calculator">2 +4</gadget>
<output>6</output>
6S=6   S=1   6=6   ANSWER:6
<result>C</result>
A player holds 13 cards of four suits, of which seven are black and six are red. There are twice as many diamonds as spades and twice as many hearts as diamonds. How many clubs does he hold ?