Answer
$x = \frac{24}{7}$ mm
Work Step by Step
In similar triangles, corresponding sides are proportional to one another.
Let us set up a proportion to find the relationship between two sides of one triangle and two sides of the other triangle:
$\frac{x}{4} = \frac{x + 6}{11}$
Cross multiply to get rid of fractions:
$11x = 4(x + 6)$
Multiply to simplify:
$11x = 4x + 24$
Subtract $4x$ from each side of the equation to move variables to one side of the equation:
$7x = 24$
Divide each side by $7$ to solve for $x$:
$x = \frac{24}{7}$ mm
