x = 8
Step-by-step explanation:
AE = 3x - 4
EC = x + 12
SInce diagonals AC and DB intersect at E
it means the lines which meet at the intersection E are equal. A and C meet at E which gives AE and EC
AE = EC
3x - 4 = x + 12
collect like terms:
3x - x = 12 + 4
2x = 16
divide both sides by 2:
2x/2 = 16/2
x = 8