To welcome the school anniversary, the school will pull ribbons around the stage (not around the ground). Given that the stage is 15m long, 10m wide, and 4.5m high, how many meters of ribbons should the school buy at least?
为迎接校庆，学校要在舞台四周拉彩带(地面的四边不拉)．已知舞台长15m，宽10m，高4.5m，学校至少需要买多少米彩带？
<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">4.5 * 4</gadget>
<output>18</output>

<gadget id="calculator">30 + 20 + 18</gadget>
<output>68</output>

<result>68</result>