a negative times a negative = a positive
so (a * b) + c = 12
(-2 * -3) +6 = 12
6+6 = 12
Answer:b=-10.5, a=31.5
Step-by-step explanation: 3b=-a , -3b=a
a+b =21
-3b+b = 21
-2b=21
b=-10.5
a=-3b
a=-3*-10.5=31.5
Just expand the terms to get general form.

Hope this helps.
The answer is - y-3=0 x (x-3)
Answer:
First box: 18
Second box: 40.5
Third box: 45
Step-by-step explanation:
9 km/m