Question

a tributary joins a river at an angle. find the value of x.
16
x = \square

Explanation:

Step1: Identify supplementary angles

The two angles \( x^\circ \) and \( (2x + 21)^\circ \) are supplementary, so their sum is \( 180^\circ \).

$$ x + (2x + 21) = 180 $$

Step2: Simplify the equation

Combine like terms:

$$ 3x + 21 = 180 $$

Step3: Solve for \( x \)

Subtract 21 from both sides:

$$ 3x = 180 - 21 = 159 $$

Divide both sides by 3:

$$ x = \frac{159}{3} = 53 $$

Answer:

\( 53 \)