计算:50÷( ﹣ + ).
解法一:原式=50÷ ﹣50÷ +50÷ =50×3﹣50×4+50×12=550.
解法二:原式=50÷( ﹣ + )=50÷ =50×6=300.
解法三:原式的倒数为( ﹣ + )÷50=( ﹣ + )× = × ﹣ × + × =
故原式=300.