我不会这几道数学题

7.8×3.2+32×22 =24.96+704 =24.96 4.75÷（0.5×7.3+0.5×27） =4.72/17.15 ≈0.27521865889 9.4×【0.96÷（5.4÷0.9）】 =9.4×0.16 =1.504