In a set of magicians cards, there are 15 red cards, and 60% more green cards. Yellow cards are as many, as the sum of red and green cards. How many cards of all mentioned colors are there?
There are 60/100 * 15 = 
<gadget id="calculator">60/100*15</gadget>
<output>9</output>
9 more green cards than red cards.
Which means there are 15 + 9 = 
<gadget id="calculator">15+9</gadget>
<output>24</output>
24 green cards.
Yellow cards make up to 15 + 24 = 
<gadget id="calculator">15+24</gadget>
<output>39</output>
39 cards.
So in total, there are 39 + 39 = 
<gadget id="calculator">39+39</gadget>
<output>78</output>
78 cards of different colors.

<result>78</result>