3 cows and 8 sheep eat a total of 93 catties of grass a day, 5 cows and 15 sheep eat a total of 165 catties of grass a day, how many catties of grass do 1 cow and 1 sheep eat a day?
3头牛和8只羊一天共吃青草93斤，5头牛和15只羊一天共吃青草165斤，1头牛和1只羊一天共吃青草多少斤？
<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">6 + 15</gadget>
<output>21</output>

<result>21</result>