[tex]1st \: day + 2nd \: day + 3rd \: day + 4th \: day = 26\frac{1}{4} \\ 6\frac{1}{3} + 9\frac{1}{2} + 5\frac{1}{4} + x = 26\frac{1}{4} \\ \frac{253}{12} + x = \frac{105}{4} \\ x = \frac{105}{4} - \frac{253}{12} \\ x = \frac{31}{6} = 5\frac{1}{6} [/tex]