Question 2
a) Suppose $\frac{bz-cy}{a}=\frac{cx-az}{b}=\frac{ay-bx}{c}$ with $abc\ne 0$. Prove $x: y: z=a: b: c$.
b) A six-digit number $\overline{abcdef}$ is divisible by 7. Prove that the six-digit number $\overline{efabcd}$ is also divisible by 7.
b) A six-digit number $\overline{abcdef}$ is divisible by 7. Prove that the six-digit number $\overline{efabcd}$ is also divisible by 7.