Title: I bought 20 pieces of sugar in Dongdong and gave 4 pieces to my sister. Now my sister is more than Dongdong 1 block. How many sweets does my sister have?
Solution: suppose my sister once had x pieces of candy,
x+4=20-4+ 1
x+4= 17
x= 17-4
x= 13
A: My sister used to have 13 candy.