• question_answer A takes 6 days less than B to do a work. If both A and B working together can do it in 4 days, how many days will B take to finish it?

 Let B can finish a work in x days so,        A can finish work in $(x-6)$ days Together they finish work in 4 days Now, $\frac{1}{x}+\frac{1}{x-6}=\frac{1}{4}$ $\frac{x-6+x}{(x)(x-6)}=\frac{1}{4}$ $4(2x-6)={{x}^{2}}-6x$ $8x-24={{x}^{2}}-6x$ ${{x}^{2}}-14x+24=0$ ${{x}^{2}}-12x-2x+24=0$ $x(x-12)-2(x-12)=0$ $(x-12)(x-2)=0$ Either $x-12=0$ or $x-2=0$ $x=12$or $x=2$, (Rejected) B can finish work in 12 days A can finish work in 6 days