Two days ago, Uncle Welly planted 50 roses on his vacant lot. Yesterday, he planted 20 more roses than the previous day. Today, he planted twice the number of roses than two days ago. How many roses did Uncle Welly plant in his vacant lot? Think carefully first, then make a decision:
Yesterday, Uncle Welly was able to plant 50 + 20 = 70 roses. Today, he planted 2 x 50 = 100 roses. Therefore, Uncle Welly has 50 + 70 + 100 = 220 roses planted on his vacant lot. So, the answer is 220.