解:5/12+7/12×4/7等于( 3/4 ),【即等于0.75】 ∵已知需求出5/12+7/12×4/7等于多少 ∴5/12 + 7/12 × 4/7 = 5/12 + 1/3 = 5/12 + (1×4)/(3×4) = 5/12 + 4/12 = 9/12 = 3/4 = 0.75 答:5/12+7/12×4/7等于3/4,【即等于0.75】