[tex] \frac{7}{72} - \frac{5}{84} - ( - \frac{13}{60}) - ( + \frac{11}{24}) = \frac{7}{72} - \frac{5}{84} + \frac{13}{60} - \frac{11}{24} = \frac{7 \times 35}{72 \times 35} - \frac{5 \times 30}{84 \times 30} + \frac{13 \times 42}{60 \times 42} - \frac{11 \times 105}{24 \times 105} = \frac{245}{2520} - \frac{150}{2520} + \frac{546}{2520} - \frac{1155}{2520} = \frac{245 - 150 + 546 - 1150}{2520} = - \frac{514}{2520} = - \frac{257}{1260} [/tex]
