[tex]15( \frac{f+1}{3}) =[/tex]
Remove parentheses [tex](a)=a[/tex]
[tex]15 \frac{f+1}{3} [/tex]
multiply fractions : [tex]a* \frac{b}{c} = \frac{a*b}{c} [/tex]
[tex] \frac{(f+1)*15}{3} [/tex]
Divide the numbers: [tex] \frac{15}{3} [/tex]
[tex]= 5(f+1)[/tex]
hope this helps!
