47/51÷31+4/51×1/31
=47/51×1/31+4/51×1/31
=(47+4)/51*31
=51/51*31
=1/31
1/5×37%+0.63×20%+45%
=0.2*0.37+0.63*0.2+0.45
=0.2*(0.37+0.63)+0.45
=0.2*1+0.45
=0.65
98%×1/4÷2%÷1/4
=98%*1/4*100/2*4
=49
7/2÷4＋60×25%
=7/2*1/4+60*1/4
=1/4*(3.5+60)
=63.5*1/4
=15.875