11. Vera bought 6 fewer notebooks than Misha and Vasya together, and Vasya bought 10 fewer notebooks than Vera and Misha together. How many notebooks did Misha buy?
11. Let Vera bought $a$ notebooks, Vasya - $b$, and Misha - $c$. Then, according to the condition, $a+6=b+c$ and $b+10=a+c$. Adding these equations term by term, we get $a+b+16=a+b+2c$ from which $2c=16$, hence $c=8$.