12-3= 14-7= 8+4= 30+70=
30+7= 42-2= 50+6= 17-9=
20-9= 55-50= 36-6= 18-9=
63-3= 25-5= 77-70= 15-6=
①3248÷16﹣8.4×2.5
②4.8×(+﹣)
③2.5×96
④64.8÷(22.4﹣1.7﹣15.3)
⑤×[14÷(﹣)]
⑥(+)÷×3.6
①(2.3+2.3+2.3+2.3)×2.5
②7.2×85%+2.8×0.85
③( + - )×24
④ ÷[ ×( - )]
⑤[( -0.25)× +0.3]÷