Answer + ! lucia finds that (3x^2 + 3x + 5) + (7x^2 - 9x + 8) = 10x^2 - 12x + 13. what error did lucia make? a. she found the difference instead of the sum. b. she combined the terms 3x^2 and 7x^2 incorrectly. c. she combined the terms 3x and –9x incorrectly. d. she did not combine all like terms.