To calculate this expression, we need to first simplify the parentheses:

17/21 + (2 1/7 * (11/36 - 13/60))

= 17/21 + (15/7 * (11/36 - 13/60)) [Convert the mixed fraction to an improper fraction]

= 17/21 + (15/7 * (5/4 - 13/60)) [Find a common denominator for the fractions in the parentheses]

= 17/21 + (15/7 * (15/12 - 13/60))

= 17/21 + (15/7 * (15/12 - 13/60))

= 17/21 + (15/7 * (15/12 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

Next, we calculate the expression within the parentheses:

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (225/180 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (45/36 - 13/60))

= 17/21 + (15/7 * (15/12 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

Now, we multiply 15/7 by the result in the parentheses:

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

= 17/21 + (15/7 * (5/4 - 13/60))

Now, we subtract the result in the parentheses from 17/21:

= 17/21 - 15/28

Finally, we subtract the fractions to find the final result:

= (1728 - 2115) / (21*28)
= (476 - 315) / 588
= 161 / 588
= 23 / 84