Answer:
Let x be the quantity of caffeine in 12 oz of soft drink (in mg )
Given,
The quantity of caffeine in 8 oz cup of coffee = 184 mg,
According to the question,
5 times of x = caffeine in 8 oz cup of coffee,
⇒ 5x = 184
Which is the required equation,
By solving it,

⇒ x = 36.8 ≈ 37,
Thus, the caffeine in 12 oz of soft drink is 37 mg.