7.5+2.5×1.2，简便运算：7.5+2.5×1.2 = 7.5 + 2.5×0.4×3 =7.5 + 1×3 =10.5
7.5+2.5×1.2，简便运算？7.5+2.5x0.3x4=10.5
7.5+2.5×(10+2)=7.5+2.5×10+2.5×2=7.5+25+5=32.5+5=37.5
