In the figure above, s || t, a = 48°, and b = 107°. what is the measure of angle c?

48+107=155
180-155=25
your answer is 25°

Let the triangle be BCA.
 b° is the supplement of ∠ CBA , since b° = 107°, then CBA = 180° - 107°=73°
So CBA = 73
But ∠ CAB = a₀ = 48° (Internal alternates)
In the triangle ABC, B=73°, A= 48°. The sum of all angles in a triangle = 180°, then 48°+73°+c₀ = 180°, and c₀ = 180 - 73 - 48 = 59°

Then ∠BAC = c° = 59°