口算8+7= 9﹣5= 12﹣12= 6+10=5+3+7= 10﹣8﹣2= 7+3﹣6= 15﹣10+6=
3÷8═= ÷24= %= :56.
3:4= :8=9: == %
3÷ == :12=七成五= %
÷10==9: == :40.
18: = :20== ÷40=1.2.