SOLUTION
In this question, we are dealing with an arithemetic progression
1,4,7,10,.....
a(first term )=1
d(common difference) = 4-1 =3 or 7-4=3
d=3
n=30
[tex]S=\frac{n}{2}(2a+(n-1)d)[/tex][tex]\begin{gathered} S=\frac{30}{2}((2\times1)+(30-1)3) \\ \text{ =15(2+(29}\times3)) \\ \text{ =15(2+87)} \\ \text{ =15(89)} \\ \text{ =1335} \end{gathered}[/tex]The sum of the first 30 terms is 1335.