(7.51÷2-2.08)×1.1=7.51×1.1÷2-(2+0.08)×1.1=7.51×(1+0.1)÷2-(2×1.1+0.08×1.1)=(7.51+0.751)÷2-(2.2+0.088)=4.1305-2.288=1.8425
(1/51+2/87)÷1/29+22÷51=(1/51+2/87)×29+22/51=1/51×29+2/87×29+22/51=(29/51+22/51)+2/3=1+2/3=1又2/3