Question

-a^2+46a-480=0
a - ?

Answer 1

multiply the equation with -
a^2-46a+480=0
(a-30) (a-16)=0
a=16 or a=30
hope that helps

Answer 2

a = 30
a = 16

-a² + 46a -480 = 0

(-a + 30) (a -16) = 0
(-a)(a) + (-a)(-16) + 30(a) + 30(-16) = 0
-a² + 16a + 30a -480 = 0
-a² + 46a - 480 = 0

(-a + 30) = 0 ; (a - 16) = 0
-a = -30 ; a = 16
a = 30

To check:
a = 30
-(30)² + 46(30) - 480 = 0
-900 + 1380 - 480 = 0
480 - 480 = 0
0 = 0

a = 16
-(16)² + 46(16) - 480 = 0
-256 + 736 - 480 = 0
480 - 480 = 0
0 = 0