There are 40pupils in a class. 30 of them study Biology, 22 study Physics and 21 study chemistry,15 study physics and Biology, 10 study Physics and chemistry, 13 study biology and chemistry, 2 study physics only, 3 study chemistry only and 7 study biology only. Represent this information on a Venn diagram.
How many pupils study all the subject.
If a student is selected at random, what is the probability that he studies either physics or chemistry.​

Find a number such that if you add 8 and divide the result by 4 you will get the same answer as if you subtracted 3 from the original number and divided by 2

Which is the graph of the piecewise function f(x)? f(x)=[tex]f(x) = \left \{ {{-x+1, x\leq 0 } \atop {x+1, x\ \textgreater \ 0}} \right.[/tex]

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?