Since they're in arithmetic progression, the difference between consecutive terms is fixed.
[tex](x + 2) - (x - 1) = 3[/tex]
[tex]3x - (x + 2) = 2x - 2 = 3 \implies 2x = 5 \implies x = \dfrac52[/tex]
Then the first term is
[tex]x-1=\dfrac52 - 1 = \boxed{\dfrac32}[/tex]
and the fifth term is
[tex]3x + 3 + 3 = 3\cdot\dfrac32 + 3 + 3 = \boxed{\dfrac21}2[/tex]
