Answer
The first six terms are:
$300, 350, 400, 450, 500. 550$
Work Step by Step
The next five terms f the sequence can be found by adding the common difference of $20$ to obtain:
$a_1=300
\\a_2=300+50=350
\\a_3=350+50=400
\\a_4=400+50=450
\\a_5=450+50=500
\\a_6=500+50=550$
