Check the picture below.
we know for the equiangular triangle, a triangle with all equal angles, 60° each, must also have all equal sides, so we can say that 2x + 13 = 5y - 8 or that all sides are 2x + 13 each or 5y - 8 each, however, the last two remaining sides, the ones you see extending in the picture, we don't have a constraint for them, because we don't know the other two angles.
We do know the linear angle between 2x + 13 and 9y - 10 is a 120°, because 60° + 120° = 180° is a flat-line, however the other two angles, that add up to 60° total, can be anything, 20° and 40°, or 17° and 43° and so on, so the length of 9y - 10 can likewise be many lengths, as the two sides keep on extending.
If we knew the containing triangle is a right-triangle, then we can say that 5y - 8 = 9y - 10, and from there we get y = 1/2, because the obtuse triangle will be an isosceles, but we don't have that info, so is not possible.