we are given
[tex] f(x)=6x+5 [/tex]
[tex] x=4y^2 -25 [/tex]
we can plug x into f(x)
[tex] f(x)=6(4y^2 -25)+5 [/tex]
now, we can simplify it
[tex] f(x)=6*4y^2 -6*25+5 [/tex]
[tex] f(x)=24y^2 -150+5 [/tex]
[tex] f(x)=24y^2 -145 [/tex]
now, we can plug y=3
[tex] f(x)=24(3)^2 -145 [/tex]
[tex] f(x)=71 [/tex].............................Answer