Grandma bought less than 20 pieces of candy, 3 yuan and 3 pieces of land still owed 1 yuan, 5 yuan and 5 pieces of land still owed 2 yuan, how many pieces of candy grandma bought back.
奶奶买回不到二十块的糖果，3块3块地数还欠1块，5块5块地数还余2块，奶奶买回多少块糖果．
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">15 + 2</gadget>
<output>17</output>

<result>17</result>