6×8=6×7+=6×9-
7×8=8×6+=8×8-
25{#blank#}1{#/blank#}5×4 6×3{#blank#}2{#/blank#}19 20{#blank#}3{#/blank#}5×8
2×6{#blank#}4{#/blank#}3×4 5×3{#blank#}5{#/blank#}5+3 5×3+5{#blank#}6{#/blank#}6×5-5