Mathias and Roman are discussing how to simplify the following expression: 7ba? + 90° - 9(143b + 2ab?). They are writing an equivalent expression before and after combining like terms. Select all the possible solutions they obtained in the process.

What is the sum of the geometric series in which a1 = 7, r = 3, and an = 1,701? hint: cap s sub n equals start fraction a sub one left parenthesis one minus r to the power of n end power right parenthesis over one minus r end fraction comma r ≠ 1, where a1 is the first term and r is the common ratio