A green belt is 20 meters long. On one side of it, a rose is planted every 4 meters (both ends are planted), and 3 jasmines are planted between every two roses. How many flowers were planted in total?
一条绿化带长20米，在它的一边每隔4米种一株月季花(两端都种)，并且在每两株月季花之间种3株茉莉花．求一共种了多少株花？
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">5 + 1 + 15</gadget>
<output>21</output>

<result>21</result>