Question 1.
[tex]f(3) = 7 \times 3 - 5 = 21 - 5 = 16[/tex]
Question 2.
[tex]f(6) = 7 \times 6 - 5 = 42 - 5 = 37[/tex]
Question 3.
[tex]f(x)=9\\7x-5=9\\7x-5+5=9+5\\7x=14\\x=14/7\\x=2[/tex]
Bonne journée !