On a bridge, there are 20 billboards on each side, each 3 meters long and 2 meters wide. The distance between two billboards is 5 meters, and the billboard near the two ends of the bridge is 50 meters away from the end of the bridge. Find the length of the bridge in meters.
在一座桥上，两侧各有20块广告牌，每块长3米，宽2米．两块广告牌之间相距5米，靠近桥两端的广告牌距离桥端是50米，求这座桥长多少米．
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">19 * 5</gadget>
<output>95</output>

<gadget id="calculator">3 * 20</gadget>
<output>60</output>

<gadget id="calculator">50 * 2</gadget>
<output>100</output>

<gadget id="calculator">95 + 60 + 100</gadget>
<output>255</output>

<result>255</result>