what is the answer?

Answer:
Now Substitute values
[tex]\longrightarrow[/tex][tex]\sf 3x-4=5x-10[/tex]
[tex]\longrightarrow[/tex][tex]\sf 5x-10=3x-4 [/tex]
[tex]\longrightarrow[/tex][tex]\sf 5x-3x=-4+10 [/tex]
[tex]\longrightarrow[/tex][tex]\sf 2x=6 [/tex]
[tex]\longrightarrow[/tex][tex]\sf x={\dfrac {6}{2}}[/tex]
[tex]\longrightarrow[/tex][tex]\sf x=3 [/tex]
[tex]\therefore[/tex][tex]\sf AB=3x-4=3\times 3-4=9-4 \\ \sf AB=5units [/tex]
Step-by-step explanation:
Side AB and Side BC are the same so we can make them equal to each other:
3x -4 = 5x -10
Subtract 3x from both sides.
-4 = 2x -10
Add 10 to both sides.
6 = 2x
Divide both sides by 2
3 = x
x = 3
Now substitute x in the expression
3x -4
3(3) -4
PEMDAS
9 - 4
Subtract
5