ANSWER
[tex]BC=26[/tex]EXPLANATION
First, let us make a sketch of the problem:
Since AB is equal in length to BC, they both have a value of x.
The total length of AD is 76. This implies that:
[tex]\begin{gathered} AB+BC+CD=AD \\ x+x+24=76 \end{gathered}[/tex]Solve for x by simplifying the equation above:
[tex]\begin{gathered} 2x+24=76 \\ 2x=76-24=52 \\ \\ x=\frac{52}{2} \\ \\ x=26 \end{gathered}[/tex]Therefore, the value of BC is:
[tex]BC=26[/tex]That is the answer.