Answer:
x = 7
Step-by-step explanation:
Similar figures have sides that are proportional. Setting up a proportion for the sides of the figures will help solve for 'x':
[tex]\frac{small}{large}=\frac{3}{6}=\frac{(x-3)}{(x+1)}[/tex]
Cross-multiply: 3(x + 1) = 6(x - 3)
Distribute: 3x + 3 = 6x - 18
Combine like terms: 21 = 3x
Solve for 'x': x = 7
