Hi Lydia N
Something about your notation did not come through but it looks your question says that Angle A and Angle B are complementary Angle A is (6x -4) degrees and Angle B is (x+17) degrees then find the measure of Angle A; is that your question?
If this is true then
Complementary angles sum to 90 degrees
(6x - 4) + (x +17) = 90
6x -4 + x + 17 = 90
If this is correct the all you need to do is combine like terms and solve for x.
Plug whatever value you get for x back into the equation for the measure of Angle A
I hope this helps please let me know if my interpretation of your question is correct.