Three cows and eight sheep eat a total of 93 kg of grass a day, and five cows and 15 sheep eat a total of 165 kg of grass a day. Xiaoqiang's family has 7 cows and 20 sheep, how many kilograms of grass should be prepared every day?
三头牛八只羊一天共吃草93千克，五头牛15只羊一天共吃草165千克．小强家养了7头牛和20只羊，每天应准备草多少千克？
<gadget id="calculator">165 * 3</gadget>
<output>495</output>

<gadget id="calculator">93 * 5</gadget>
<output>465</output>

<gadget id="calculator">495 - 465</gadget>
<output>30</output>

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">45 - 40</gadget>
<output>5</output>

<gadget id="calculator">30 / 5</gadget>
<output>6</output>

<gadget id="calculator">6 * 8</gadget>
<output>48</output>

<gadget id="calculator">93 - 48</gadget>
<output>45</output>

<gadget id="calculator">45 / 3</gadget>
<output>15</output>

<gadget id="calculator">15 * 7</gadget>
<output>105</output>

<gadget id="calculator">20 * 6</gadget>
<output>120</output>

<gadget id="calculator">105 + 120</gadget>
<output>225</output>

<result>225</result>