In an isosceles triangle, there are two sides that are congruent.
In this case, AB and BC are congruent.
Knowing this, we know that AB = BC
Since we know the values of AB and BC, we can put them into the equation:
3x - 4 = 5x - 10
Subtract 3x from both sides:
-4 = 2x - 10
Add 10 to both sides to isolate 'x':
6 = 2x
Divide both sides by 2:
x = 3
Now that we know the value of the variable, we just have to input it into AB's equation:
3x - 4 = 3(3) - 4
3(3) - 4 = 9 - 4
9 - 4 = 5
AB = 5
Good luck!