The clothing store bought 40 skirts and 18 sets of children's clothing. It costs 2160 yuan to buy skirts and 1890 yuan to buy children's clothes. How much is each set of children's clothing more expensive than each skirt?
服装店进了40条裙子和18套童装．买裙子用去2160元，买童装用去1890元．每套童装比每条裙子贵多少元？
<gadget id="calculator">1_890 / 18</gadget>
<output>105</output>

<gadget id="calculator">2_160 / 40</gadget>
<output>54</output>

<gadget id="calculator">105 - 54</gadget>
<output>51</output>

<result>51</result>