What is x- intercept of the equation 7x + 3y = 21

Apolygon is shown on the graph: a polygon is shown on the coordinate plane. vertices are located at 3 comma 5, 1 comma 3, 1 comma 1, 2 comma 0, 4 comma 0, 5 comma 1, and 5 comma 3. what effect will a translation 3 units down and 2 units left have on the polygon? be sure to address how it could impact the angles, side lengths, and congruency between the original pre-image and the image. xd i need