The school brought a pile of sand, (5/9) tons were used to build roads, (1/4) tons were used to build flower beds, and (5/4) tons remained. How many tons less sand was used than was left?
学校运来一堆沙子，修路用去(5/9)吨，砌花坛用去(1/4)吨，还剩下(5/4)吨．用去的沙子比剩下的沙子少多少吨？
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(5/9) + (1/4)</gadget>
<output>29/36 = around 0.805556</output>

<gadget id="calculator">(5/4) - (29/36)</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>