卖了多少辆?

12－4={#blank#}1{#/blank#}

7－3={#blank#}2{#/blank#}

13－5={#blank#}3{#/blank#}

8＋7={#blank#}4{#/blank#}

8－7={#blank#}5{#/blank#}

40＋{#blank#}1{#/blank#}＜100

80－{#blank#}2{#/blank#}＞40

  {#blank#}1{#/blank#} - {#blank#}2{#/blank#} = {#blank#}3{#/blank#}

40+30=       78-6=         42+5=                6+53=

53+40=       39-20=        7+42=                69-8=

57-6=        88-40=       31+（46-40）=      57-30-7=

25+20-13=     62-12+21=     35+2+30=          8-（27-20）=