Angles ABC and DBA are supplementary. If m<ABC =x+1 and m<DBA = 2x-6, find the measurement of angle DBA.
Supplementary angles add up to 180°.
That means that 180 = (2x-6) + (x+1). Re-arrange this equation to solve for x. Then put that value of x into the expression 2x - 6 to solve your question.
Hope this helps!
Stephen La Rocque.