Which line from "What to the Slave is the Fourth of July.?" supports Douglass's claim that the Fourth of July is not a cause worthy of celebration by all?
O Fellow Citizens, I am not wanting in respect for the fathers of this republic. The signers of the Declaration of
Independence were brave men. They were great men, too great enough to give frame to a great age.
O Would to God, both for your sakes and ours, that an affirmative answer could be truthfully returned to these
questions! Then would my task be light, and my burden easy and delightful.
O Fellow-citizens, above your national, tumultuous joy, I hear the mournful wail of millions! whose chains, heavy and
grievous yesterday, are, to-day, rendered more intolerable by the jubilee shouts that reach them,
But, I submit, where all is plain there is nothing to be argued. What point in the anti-slavery creed would you have
me argue? On what branch of the subject do the people of this country need light?

The line from "What to the Slave is the Fourth of July?" which supports Douglas' claim that the Fourth of July is not a cause worthy of celebration by all is:

O "Fellow-citizens, above your national, tumultuous joy, I hear the mournful wail of millions! whose chains, heavy and  grievous yesterday, are, to-day, rendered more intolerable by the jubilee shouts that reach them."

Explanation:

The renowned American abolition advocate and civil rights fighter, Frederick Douglas delivered the above-named keynote address to the Rochester Ladies' Anti-Slavery Society on Independence Day July 5, 1852.  Essentially, Douglas invited Americans to improve themselves.  In addition, he stressed the need for citizens to exercise their voting franchise, because as someone said elsewhere, "voting is a great equalizer" for a just and egalitarian society.

that the mashine was talking hahahaha

right angles are formed by perpendicular lines. if the lines would extend, to make two intersecting lines, they would form four right angles.