小朋友站成一排共29人，我左边有20人，右边有多少人？'w4Y:W1H+[+@6|.b4t8Z(C
算式：提示-z:],O5x5?2G)v'w4Y:W1H+[+@6|.b4t8Z(C
答：右边有4H5r'I'@6i4k7B1p人。'w4Y:W1H+[+@6|.b4t8Z(C