What is the sum of the geometric sequence 2, 10, 50, ... if there are 7 terms?

Common ratio = 10/2 = 5.

First term = 2.

Sum of the first n terms of a G.S. is \(\dfrac{a (r^n - 1)}{r - 1}\), where a is the first term and r is the common ratio.

Can you substitute a = 2, r = 5, n = 7 and try to proceed from here?