Answer
$\left\{\begin{array}{ll} 2 & \quad if & \quad 0\leq x\leq1 \\ 2(x-1)+2 & \quad if & \quad x\gt1 \end{array} \right. $
Also see the image below.
Work Step by Step
According to the information given, we can write:
$C(x)=\left\{\begin{array}{ll} 2 & \quad if & \quad 0\leq x\leq1 \\ 0.2\times10(x-1)+2 & \quad if & \quad x\gt1 \end{array} \right. $
$=\left\{\begin{array}{ll} 2 & \quad if & \quad 0\leq x\leq1 \\ 2(x-1)+2 & \quad if & \quad x\gt1 \end{array} \right. $
See the image above