Answer is base angles will both be 48 degrees.
Step by step
The base angles are the 2 congruent angles in an isosceles triangle.
Sum of the interior angles =180 degrees.
The vertex is 84, so we know one angle.
180 - 84 = 96
Since the base angles will be equal, we divide 96 by 2 = 48.
The base angles will each be 48 degrees.
