1-(4-a)(9-a)-(a+3)(a-5)= 1-(36-4a-9a+a²)-(a²-5a+3a-15)= 1-36+4a+9a-a²-a²+5a-3a+15= -2a²+15a-20
-2(-10)²-15*10-20= -200-150-20= -370
1-(4-a)(9-a)-(a+3)(a-5)= 1-(36-4a-9a+a²)-(a²-5a+3a-15)= 1-36+4a+9a-a²-a²+5a-3a+15= -2a²+15a-20
-2(-10)²-15*10-20= -200-150-20= -370