1.Let SnS_nSn denote the sum of first nnn terms of an arithmetic progression. If S20=790S_{20} = 790S20=790 and S10=145S_{10} = 145S10=145, then S15−S5S_{15} - S_5S15−S5 is:a.395395395b.390390390c.405405405d.410410410Login to continueOnly logged in users canattempt or see the solution.
