Every time you want to add 2 fractions, they need to have the same denominator.
Since 8 and 5 are not factors of the same number, you multiply 3/5 by 8, and 3/8 by 5. So you get:
[tex] \frac{3*8}{5*8} + \frac{3*5}{8*5} [/tex]
[tex] \frac{24}{40} + \frac{15}{40} [/tex]
[tex] \frac{24+15}{40} [/tex]
[tex] \frac{39}{40} [/tex]
Hope this Helps! :D
