Answer:
Upper left 10, upper right 2, lower left 3, lower right 3.
Explanation:
they give us the upper left and lower right in the first two bullet points. Then “in total, 12 girls can sing”. 12 - the 10 who can sing and dance = 2 for upper right.
They also say there are 18 girls total. 18 - 10 - 3 = 3 for the lower left