(1)3.2×1.3=4.16(元)答:花了4.16元.(2)100-17.2×2.8=100-48.16=51.84(元)答:应找回51.84元.(3)35÷10=3.5(千克)答:最多可买3.5千克.(4)王奶奶青椒与西红柿各买了4千克,西红柿比青椒多花多少钱?(5.5-3.2)×4=2.3×4=9.2(元)答:多花了9.2元.