Answer
See below.
Work Step by Step
$a_n=7+4(n-1)$, thus
$a_1=7+4(1-1)=7+4\cdot0=7+0=7$
$a_2=7+4(2-1)=7+4\cdot1=7+4=11$
$a_3=7+4(3-1)=7+4\cdot2=7+8=15$
$a_4=7+4(4-1)=7+4\cdot3=7+12=19$
$a_5=7+4(5-1)=7+4\cdot4=7+16=23$
$a_6=7+4(6-1)=7+4\cdot5=7+20=27$