Answer:
Draw a Ven diagram ie a rectangle with 2 circles one for F and the other for C the intersection overlap will have the 10 who play both outside the circles but within the rectangle the 7 who play neither so then fill the rest of F with 4 to give a total of 14 and 11 for the C to total 21. When you add all the numbers you’ll get the class total of 32. Then the % who play both F and C is = (10/32)*100 = 31.25%