Subtract -7a^2+3a-9−7a
2
+3a−9minus, 7, a, squared, plus, 3, a, minus, 9 from 5a^2-6a-45a
2
−6a−45, a, squared, minus, 6, a, minus, 4.

You will subtract these top 2

- 7 {a}^{2}  + 3a - 9 - 7 {a}^{2}  + 3a - 9

5 {a}^{2}  - 6a - 45 {a}^{2}  - 6a - 4

and this bottom one is your ANSWER

- 12 {a}^{2}  - 110a - 22

114 plus 113 times 2 and 114 times 3