question 1) solve 6x^2 congruent 6 (mod 16) question 2) system of equations {2x + 5y congruent 1 (mod 13) {5x + y congruent 2 (mod 13) question 3) system of equation {8x + 3y congruent 9 (mod 12) {6x + 5y congruent 2 (mod 12)