简便的20道分数四则混合运算

45 × 2/3 + 1/3 × 15 27.7/19 + 12/19 × 5/6 28.1/4 + 3/4 ÷ 2/3 29.8/7 × 21/16 + 1/2 30.101 × 1/5 ? 1/5 × 21 3.(23/4-3/4)*(3*6+2) 4.3/7 × 49/9 - 4/3 5.8/9 × 15/36 +