hello\
phan so hoc sinh gioi cua lop
1-(\(\dfrac{7}{15}\)+\(\dfrac{1}{3}\))=1-(\(\dfrac{7}{15}\)+\(\dfrac{5}{15}\))=1-\(\dfrac{12}{15}\)=1-\(\dfrac{4}{5}\)=\(\dfrac{5}{5}\)-\(\dfrac{4}{5}\)=\(\dfrac{1}{5}\)(ban)
b)so hoc sinh cua lop do la
9:\(\dfrac{1}{5}\)=9.5=45(ban)
so hoc sinh kha la
45.\(\dfrac{1}{3}\)=15 (hoc sinh)
so hoc sinh trung bimh la
45.\(\dfrac{7}{15}\)=21(ban)
D/S a)\(\dfrac{1}{5}\)
b)so hoc sinh trung binh 21
so hoc sinh kha laa 15