Question

1. b •——• c ———• d, where the length from b to c is ( x + 2 ), from c to d is ( x + 11 ), and the total length from b to d is 13.

Explanation:

Step1: Set up the equation

From the number line, we know that \( BC + CD = BD \). So, \( (x + 2)+(x + 11)=13 \).

Step2: Simplify the left side

Combine like terms: \( x + 2+x + 11 = 2x+13 \). So the equation becomes \( 2x + 13 = 13 \).

Step3: Solve for x

Subtract 13 from both sides: \( 2x+13 - 13=13 - 13 \), which simplifies to \( 2x = 0 \). Then divide both sides by 2: \( x=\frac{0}{2}=0 \).

Answer:

\( x = 0 \)