+=                                                    +=                                 

  +=                               +=                                   +=   

5{#blank#}1{#/blank#}3        3{#blank#}2{#/blank#}2-1          5-2{#blank#}3{#/blank#}2

4{#blank#}4{#/blank#}5        2+3{#blank#}5{#/blank#}5-3       5-0{#blank#}6{#/blank#}5+0

左边有{#blank#}1{#/blank#}只小鸡，右边有{#blank#}2{#/blank#}只小鸡。一共有几只小鸡?

□○□=□（只）{#blank#}3{#/blank#}