#### Answer

$y= 3.5$ units

#### Work Step by Step

Step 1: Since the triangles are similar, their corresponding sides are in
proportion.
Step 2: This means that $\frac{7}{14}=\frac{5}{10}=\frac{y}{7}$.
Step 3: Since the corresponding sides are in proportion, we can take any set of known sides and equate it to the set of sides containing the unknown.
Step 4: Therefore, $\frac{5}{10}=\frac{y}{7}$.
Step 5: Solving through cross multiplication: $10y=5\times7$.
Step 6: $10y=35$.
Step 7: $y= 3.5$ units.
Check:
Step 1: Equating the three proportions to see if they reduce to the same fraction: $\frac{7}{14}=\frac{5}{10}=\frac{3.5}{7}$.
Step 2: $\frac{1}{2}=\frac{1}{2}=\frac{1}{2}$.
Step 3: Therefore, the answer is accurate.