A zoo has 30 species of birds. Out of these, 6 cannot fly. How many species of birds at that zoo can fly?
A preparatory school has 516 students. 180 of them are in the 1st year, while 139 are in the 3rd year. How many students are in the 2nd year?
A company has 589 employees. 265 of them are female employees. 159 of the total employees are under 30 years old and 63 of them are females. How many male employees are above 30 years old?