7.1 Little Dima has two more teeth than little Yulia. Boxer Kolya has as many teeth as Dima and Yulia combined, but half as many as biologist Vanya. In total, they have 64 teeth. How many teeth does each of them have?
Solution: Dima has $x$ teeth, Yulia has $x-2$, Kolya has $x+x-2=2 x-2$, Vanya has $2 \cdot(2 x-2)=4 x-4$. In total, $x+x-2+2 x-2+4 x-4=8 x-8=64 . x=9$.

Number of teeth: D -9, Y $-7, K-16$, V -32.