I'm currently revising Vectors and am a little stuck. I am watching through a MathsWatch clip and got stuck when multiplying a negative in a bracket. AS you can see at the end of question B they ended up with: 1/3y + 2/3x, however I ended up with 2/3x-1/3y when following AC to CT. What did I do wrong?
Multiply the value $\frac{2}{3}$ with each term within the brackets, namely $x$ and $-y$ (notice you have to keep the negative sign). You should get
$$y + \frac{2}{3}(x-y) = y + \frac{2}{3}x - \frac{2}{3}y$$
Group together the y:s to get $\frac{1}{3}y + \frac{2}{3}x$.