一年级数学（下册）进位，借位混合 21-5= 44+7= 67-8= 7+27= 52-3= 1+69= 24-7= 67+3= 26-8= 8+78= 4+67= 55+6= 47-8= 78+3= 42-3= 31-9= 54-6= 8+28= 9+75= 74-8= 61-4= 94-7= 87-8= 52+9= 33+8= 35-7= 42+9= 28+2= 31-7= 19+7= 24-8= 56-7= 67+7= 34+9= 23-5= 37-9= 45+9= 38+8= 29+7= 42-7= 73-7= 17+6= 25+6= 76-9= 43-9= 55-7= 37+9= 48+2= 49+7= 62-8=