(1/3+2/5+3/7+4/9)/(4/3+8/5+12/7+16/9)

问题描述:

(1/3+2/5+3/7+4/9)/(4/3+8/5+12/7+16/9)

分子和分母同时乘以(3*5*7*9)得(1+2+3+4)/(4+8+12+16)=0.25