There are 50 girls in a dance group in a private school. 30% of them dance hip hop and 80% dance ballet. How many of them dance both hip hop or ballet? Choose the correct choice from the following options.
A) 5	B) 10	C) 15	D) 20	E) 25
The total number of girls in the class is n = 50.   The number of girls dancing hop hop is 30% of it, thus   n (A)=30/100×50=30/2= 
<gadget id="calculator">30/2</gadget>
<output>15</output>
15.   The number of girls dancing ballet is 80%, thus   n (B)=80/100×50=80/2= 
<gadget id="calculator">80/2</gadget>
<output>40</output>
40.   In order to calculate the number of girls dancing both hip hop and ballet we can use the following equation:   n (AnB)=n (A)+n (B) -n =15+40-50= 
<gadget id="calculator">15+40-50</gadget>
<output>5</output>
5.   So, 5 girls in this dance class dance both hip hop and ballet.   5NSWER: 5
<result>A</result>
There are 50 girls in a dance group in a private school. 30% of them dance hip hop and 80% dance ballet. How many of them dance both hip hop or ballet?