Answer:
~ 84 cm of the pop in the poster ~
Explanation:
Let us plan out our steps, and solve for each:
1. Given the information, let us create a proportionality as such:
7 = 1 ⇒ x - centimeters of the pop in the poster
x 12
2. Now let us cross multiply, and solve through simple algebra for x:
7 * 12 = x,
x = 84 centimeters of the pop in the poster