1. The problem statement, all variables and given/known data Find n. 5a + 10d = 26 5a + 5/2(n-1)d + 5/2(n-5)d = 726 n/2(2a + (n-1)d) = 10904 Note that a and d are unknowns as well. 2. The attempt at a solution It is extremely tedious to calculate by hand. Furthermore, my calculator is only able to solve both linear equations and quadratic equations in the form of ax + b and ax^2 + bx + c respectively, where a, b and c are known constants. However, the above equations give me unknowns like nd, na, which I am unable to key it into the calculator. Hence, is there a better way to solve the above equations? Much help appreciated. Thanks!