In an isosceles triangle, the two sides opposite the congruent angles are also congruent.
So, to solve this problem, start by identifying the sides that are opposite the congruent angles and identifying their expressions.
These are 2x - 5 and x + 10
As far as we know, the expression for the base of the isosceles triangle is extraneous information put there to distract you. (They do that a lot in maths like geometry and trigonometry to make sure you understand your theorems)
From here, since we already know that these sides are congruent , we can set the expressions equal to one another.
This should look like:
2x - 5 = x + 10.
Now, solve for x. Start by adding 5 to both sides to keep the equation balanced.
This results in:
2x = x + 15
Now, subtrat the x from the right side of the equation and the left side of the equation.
This leaves you with:
15 = x.
So, your value for x in this isosceles triangle is 15.
I hope this helps! :)