10×10+8×8=164 10×10÷2+(10+8)×8÷2 =50+72 =122 164-122=42 6×6+4×4=52 6×6÷2+(6+4)×4÷2 =18+20 =38 52-38+(6-4)×4÷2 =18 4×4+3×3=25 4×(4+3)÷2+3×3÷2 =14+4.5 =18.5 25-18.5=6.5