Mathematics - Pre-Algebra - Evaluating expressions - Evaluate the Expression

15 problems with increasing complexity. (1) Simple: 'x + 8 when x=5' (13). (2) Two operations: '3x - 4 when x=6' (14). (3) Exponents: 'x² + 1 when x=4' (17). (4) Two variables: 'xy + z when x=3, y=2, z=5' (11). (5) Negative values: '2a - b when a=-3, b=4' (-10). Show substitution step for wrong answ