There are angles whose measures add to 180° . Their measures are: m∠A=67° , m∠B=(2x+20)° , and m∠C=x° . What is the measure of ∠B ? Please

1 answer

To find the measure of angle \( B \), we first set up the equation based on the fact that the measures of angles \( A \), \( B \), and \( C \) add up to \( 180^\circ \):

\[ m\angle A + m\angle B + m\angle C = 180^\circ \]

Substituting the given expressions:

\[ 67^\circ + (2x + 20)^\circ + x^\circ = 180^\circ \]

Now, we combine the like terms:

\[ 67 + 2x + 20 + x = 180 \]

Simplifying the left side:

\[ 87 + 3x = 180 \]

Next, we isolate \( x \) by subtracting \( 87 \) from both sides:

\[ 3x = 180 - 87 \]

This simplifies to:

\[ 3x = 93 \]

Now, we divide both sides by \( 3 \):

\[ x = 31 \]

Now that we have the value of \( x \), we can find the measure of angle \( B \):

\[ m\angle B = 2x + 20 \]

Substituting the value of \( x \):

\[ m\angle B = 2(31) + 20 \]

Calculating this gives:

\[ m\angle B = 62 + 20 = 82^\circ \]

Thus, the measure of angle \( B \) is:

\[ \boxed{82^\circ} \]