Question 1161332
looks like an arithmetic sequence.
with an arithmetic sequence, An = A1 + (n-1) * d
Sn = n * (A1 + An) / 2
in your problem, A1 = 10 and d = 4 and n = 7
A7 = 10 + 6 * 4 = 34
S7 = 7 * (10 + 34) / 2 = 7 * 44 / 2 = 7 * 22 = 154.
looks like you're good to go.