To solve this problem, first we have to find the measure of <BAC. To do this, we must set up an equation that represents that <BAC and <DAB are supplementary, meaning their sum is 180 degrees. Since we know that <DAB is 123 degrees, we can make our equation: 180 = 123 + m<BAC. To solve this equation, we simply just subtract 123 from both sides, making your answer: m<BAC = 57 degrees.
Next, we must use our knowledge that the three inner angles of a triangle must add up to a total of 180 degrees. Therefore, 180 = 58 + 57 + x, using our knowledge from previous work and the values from the figure. If we combine like terms on the right side of the equation, we get: 180 = 115 + x. Our final step is to subtract 115 from both sides to get the variable x alone, so we get: x=65.
Therefore, your answer is x=65 degrees.
Hope this helps!