831-112=        526-152=        650-338=        734-374=  

635-345=        945-436=       321-114=          374-168=

{#blank#}1{#/blank#}    {#blank#}2{#/blank#}      {#blank#}3{#/blank#}    {#blank#}4{#/blank#}

7.2－1.8

+ =             - =          1- =          + =

168÷8=            20×40=         125×8=           32×40=

37+9＝        72÷9＝      83﹣18＝    62﹣36＝

67+13＝     530﹣360＝    6×6＝      74+45＝

95﹣61＝       40+36＝      56+21≈

914﹣472≈     789﹣306≈     632+148≈