A and B completed a work together in 5 days. Had A worked at twice the speed and B at half the speed, it would have taken them four days to complete the job. How much time would it take for A alone to do the work? 

Two typists of varying skills can do a job in $6$minutes if they work together. If the first typist typed alone for 4 minutes and then the second typist typed alone for $6$minutes, they would be left with $1/5$ of the whole work. How many minutes would it take the slower typist to complete the typing job working alone? 

Three cooks have to make $80$idlis. They are known to make $20$pieces every minute working together. The first cook began working alone and made $20$pieces having worked for some time more than three minutes. The remaining part of the work was done by the second and the third cook working together. It took a total of $8$minutes to complete the $80$idlis. How many minutes would it take the first cook alone to cook $160$idlis for a marriage party the next day? 

Mini and Vinay are quiz masters preparing for a quiz. In $x \mathrm{minutes}$, Mini makes $y$ questions more than Vinay. If it were possible to reduce the time needed by each to make a question by two minutes, then in $x \mathrm{minutes}$ Mini would make $2y$ questions more than Vinay. How many questions does Mini make in $x \mathrm{minutes}$?