What algebraic propertiy am i using for 5(d + 1)

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83

Will give brainliestbased on the topographic map of mt. st. helens, what is the contour interval if the volcano height is 2,950 m?

Line u passes through points (-52, -18) and (-29, 53). line v passes through points (90, 33) and (19, 56). are line u and line v parallel or perpendicular?