①(2480-326)÷326=2154÷326≈6.607=660.7%;②(1980-668)÷1980=1312÷1980≈0.663=66.3%;③(2480-1980)÷1980=500÷1980≈0.253=25.3%;④(2480-1980)÷2480=500÷2480≈0.202=20.2%;答:①冰箱比电风扇贵660.7%,②洗衣机比电视机便宜66.3%,③冰箱比电视机贵25.3%,④电视机比冰箱便宜20.2%.