The price of a box of steel nails is 4 yuan and 50 cents. The master worker bought 15 boxes of steel nails. How much should he pay in total?
一盒钢钉的价钱是4元5角，工人师傅买了15盒钢钉，一共要付多少钱？
<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 + (1/2)</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">(9/2) * 15</gadget>
<output>135/2 = around 67.5</output>

<result>135/2 = around 67.5</result>