$\"\"$

\

Observe the figures, The corresponding angles are equal measures, $\"\"$ .

\

The lengths of the corresponding sides are proportional.

\

The corresponding sides of similar triangles are proportional $\"\"$ .

\

$\"\"$ (Substitute c = 15,d = 7, f = 5)

\

$\"\"$ (Apply cross product: $\"\"$ )

\

$\"\"$ (Multiply: $\"\"$ ) $\"\"$

\

Apply division property of addition: If a = b then $\"\"$ .

\

$\"\"$ (Divide each side by 5)

\

$\"\"$ (Cancel common terms)

\

$\"\"$ (Divide: $\"\"$ ) $\"\"$

\

The corresponding sides of similar triangles are proportional $\"\"$ .

\

$\"\"$ (Substitute a = 21,d = 7, e = 9)

\

$\"\"$ (Apply cross product: $\"\"$ )

\

$\"\"$ (Multiply: $\"\"$ ) $\"\"$

\

Apply division property of addition: If a = b then $\"\"$ .

\

$\"\"$ (Divide each side by 7)

\

$\"\"$ (Cancel common terms)

\

$\"\"$ (Divide: $\"\"$ ) $\"\"$

\

The missing measures are a = 21 and b = 27.