（8.4-7.2）x（19/6+7.5）=1.2x19/6+1.2x15/2=0.2x19+0.6x15=3.8+9=4.7
25x【（4-11/6）÷3.25]
=25x3.25÷(13/6)=25x3.25x6÷13
=25x4x3.25x3÷26
=325x3÷26
=37.5