The walls in the classrooms will be repainted during the school summer break. The area to be painted in our classroom room is about 90 square meters. For the first time, 0.5 liters of paint is required per square meter, and the required paint is only (2/3) of the first pass when painting for the second time. How many liters of paint are required for painting twice?
学校暑假期间将对教室内的墙壁重新粉刷．我们教室房间要粉刷的面积约为90平方米．第一次每平方米需用涂料0.5升，第二遍粉刷时所需涂料仅为第一遍时的(2/3)，粉刷两遍共需涂料多少升？
<gadget id="calculator">90 * 0.5</gadget>
<output>45</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">45 * (2/3)</gadget>
<output>30</output>

<gadget id="calculator">45 + 30</gadget>
<output>75</output>

<result>75</result>