A batch of fruit is transported by car, and the ratio of the tonnage to the total weight on the first day is 1:3. If another 15 tons are transported, half of this batch of fruits can be transported. How many tons is this batch of fruit?
用汽车运一批水果，第一天运的吨数与总重量的比是1：3．如果再运15吨，就可以运完这批水果的一半．这批水果共有多少吨？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">15 / (1/6)</gadget>
<output>90</output>

<result>90</result>