EXTRA POINTS! FIND THE MISSING DIMENSION! NEED ASAP

Answer:
x = 10.5 in
Step-by-step explanation:
The rectangles are similar, thus the ratios of corresponding sides are equal.
that is [tex]\frac{7}{2}[/tex] = [tex]\frac{x}{3}[/tex] ( cross- multiply )
2x = 21 ( divide both sides by 2 )
x = 10.5