A carpentry factory wants to produce a batch of tables and chairs. It originally planned to produce 60 pieces per day, but actually produced 4 more pieces per day than the original plan. As a result, the task was completed one day ahead of schedule. How many tables and chairs were originally planned to be produced?
一个木器厂要生产一批桌椅，原计划每天生产60张，实际每天比原计划多生产4张，结果提前一天完成任务，原计划要生产多少张桌椅？
<gadget id="calculator">60 + 4</gadget>
<output>64</output>

<gadget id="calculator">4 - 60</gadget>
<output>-56</output>

<gadget id="calculator">60 + (-56)</gadget>
<output>4</output>

<gadget id="calculator">64 / 4</gadget>
<output>16</output>

<gadget id="calculator">60 * 16</gadget>
<output>960</output>

<result>960</result>