So it is a line of symmetry. 8x5=40 so the area of one is 40.
Work is attached. Hope it helps!
In plain and short, we simply divide 5 by (1+2+3) and then distribute the pieces likewise

add the ratios up, and you'll get 5.
Because the left side is eclipsed in an absolute value, we have two possible values of x, denoted by:
2x+4 = 12 and -(2x+4) = 12
Solving for both of these, we are presented with the two values of x:
x = 4 and x = -8