Answer:
The number is 3.
Step-by-step explanation:
To find : A number which decreased by 12 equals 3 times it’s opposite ?
Solution :
Let the number be 'x'.
It's opposite is '-x'.
A number which decreased by 12 equals 3 times it’s opposite
i.e. 
Solving the equation,





Therefore, the number is 3.
Answer:
108 cm^2
Step-by-step explanation:
rectangle + 2 triangle = total area
L x W + 2 * 1/2 base * height = total area
(5x12) + 2 * 1/2 * 12 * 4 = total area
60 + 48 = 108 cm^2