Bamboo grows about 0.4 decimeters per hour during the vigorous growth period; bell-shaped fungus grows faster, about 2.5 decimeters per hour during the vigorous growth period. If they are all in the vigorous growth period, the height of the bamboo is 3.2 decimeters at the beginning, and the height of the bell-shaped bacteria is 0.05 decimeters. After how many hours, the height of the bell fungus can catch up with the bamboo?
竹子在生长旺盛期每小时约增高0.4分米；钟状菌生长更快，生长旺盛期每小时约增高2.5分米．如果它们都在生长旺盛期，开始时竹子高3.2分米，钟状菌高0.05分米．多少小时后，钟状菌的高度可以赶上竹子？
<gadget id="calculator">3.2 - 0.05</gadget>
<output>3.15</output>

<gadget id="calculator">2.5 - 0.4</gadget>
<output>2.1</output>

<gadget id="calculator">3.15 / 2.1</gadget>
<output>1.5</output>

<result>1.5</result>