23－7={#blank#}1{#/blank#}

31－9={#blank#}2{#/blank#}

76－8={#blank#}3{#/blank#}

63－9={#blank#}4{#/blank#}

90－6={#blank#}5{#/blank#}

20+{#blank#}1{#/blank#}=26        14-{#blank#}2{#/blank#}=6       13-{#blank#}3{#/blank#}<8

{#blank#}4{#/blank#}-9=50         8+{#blank#}5{#/blank#}=98      {#blank#}6{#/blank#}+5>12

8月共有31天，有几个星期零几天？

90-50+3890-50+38              9角1元                  4×32×6

2×42+2+2+2                        19分2角                  3+23×2