The sum of twice a number and three is 21

Atrain leaves little? rock, arkansas, and travels north at 90 kilometers per hour. another train leaves at the same time and travels south at 80 kilometers per hour. how long will it take before they are 680 kilometers? apart?

Which point-slope form equation represents a line that passes through (3,-2) with a slope of -4/5

Jubal wrote the four equations below. he examined them, without solving them, to determine which equation has no solution. which of jubal’s equations has no solution hurry