The original grain tonnage ratio between warehouses A and B is 5:4. After warehouse A transports 36 tons, the grain tonnage ratio between the two warehouses is 3:4. How many tons of grain did warehouse A originally have?
甲、乙两个仓库原有粮食吨数之比是5：4，甲仓库运走了36吨后，两个仓库的粮食吨数之比是3：4，甲仓库原来有多少吨粮食？
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(5/4) - (3/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">36 / (1/2)</gadget>
<output>72</output>

<gadget id="calculator">72 * (5/4)</gadget>
<output>90</output>

<result>90</result>