13-((4/5)+(6/8))
Make your fractions have common denominators
13-((32/40)+(30/40))
Add your fractions and simplify
13-(62/40)
or
13-(31/20)
or
13-(1 11/20)
Then turn 13 into a fraction with a common denominator! Im going to use the second fraction method (31/20)
13 written as a fraction is 13/1, its LCD with 31/20 is 20. I now multiply the top and bottom by 20
260/20
Now I rewrite the problem again
(260/20)-(31/20)
Which equals
229/20!
This is your unsimplified answer
Finally you simplify and get
11 9/20