解:75一6等于( 69 ) ∵已知需求出75一6等于多少 X - Y = Z ∴75 - 6 = (70 + 5)- (10 - 4) = 70 + 5 - 10 + 4 = (70 - 10)+ (5 + 4) = 60 + 9 = 69 75一6等于69