In a class there are x amount of students. z amounts of these students are ( y+1 ) years old. The rest of the students are y years old. Write an expression for the sum of all their ages. Simplify.

Can someone me out here number 4 plz

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?

Rewrite 9 log, x2 in a form that does not use exponents. 9log, x = log, x