Finding the Value of x in Supplementary Angles

In the figure below, two lines intersect at point O, forming four angles: angle A, angle B, angle C, and angle D. Angle A measures $$3x + 15^{ ext{°}}$$ and angle B measures $$4x - 5^{ ext{°}}$$. If angles A and B are supplementary, what is the value of $$x$$?

Recall that supplementary angles add up to $$180^{ ext{°}}$$.