For this, you will be using proportions. And in this case, the proportion will be

Firstly, cross-multiply:

Next, subtract 5x on each side:

Lastly, subtract 24 on each side, and your answer will be 6 = x
To find BC, just add 4 and 6 together, which is 10. And to find AC, add 10 and 2 together, which is 12.
In short, the answer is the first option.