Answer:
∠CBA = 60.9°
Explanation:
If you're seeking assistance from a web site for solving triangles, it works well to use one specific to that purpose. The attached shows the result for what we think you're describing.
∠CBA = 60.9°
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Since you have two sides and the angle opposite one of them you can find the angle opposite the other using the Law of Sines.
(sin B)/b = (sin C)/c
sin B = (b/c)sin C
B = arcsin(b/c·sin(C)) = arcsin(23/26·sin(99°)) = arcsin(0.873824)
B ≈ 60.8943° ≈ 60.9°
Angle CBA is about 60.9°.