Diketahui f (x) = 3x – 5. Nilai f (5p – 1) =

3 ( 5p - 1 ) - 5 = 15p - 3 - 5
                        = 15p - 8

f (5p-1)=3×(5p-1)-5
=15p-3-5
=15p-8
5p-1= 15p-8
5p-15p=-8+1
-10p=-7
p=- 10/-7
p=10/7
×=5p-1
=5×10/7-1
=50/7-1
=7 1/7-1
=6 1/7
f (6 1/7)= 3×43/7-5
=129/7-5
=129/7-35/7
=94/7
=13 3/7