In a certain area, the electricity price is 0.3 yuan per kWh during peak and valley hours (9:00 p.m. to 8:00 a.m.), and 0.52 yuan per kwh during peak hours (8:00 a.m. to 9:00 p.m.). Wang Tao's family paid an electricity bill of 35.8 yuan last month. Among them, the electricity consumption is 50 kwh during the off-peak hours, how much is the electricity consumption of his house during the peak time of this month?
某地区实行了峰谷，谷时(晚9时～早晨8时)，电价每度0.3元；峰时(早晨8时～晚9时)，电价每度0.52元．王涛家上月交电费35.8元．其中谷时用电50度，他家这个月峰时用电多少度？
<gadget id="calculator">0.3 * 50</gadget>
<output>15</output>

<gadget id="calculator">35.8 - 15</gadget>
<output>20.8</output>

<gadget id="calculator">20.8 / 0.52</gadget>
<output>40</output>

<result>40</result>