Which is the characteristic of a line

Measures of the angle of r, 31 s (x+4) t (3x+9)

The larger of two number is 4 less than twice the smaller number. the sum is 41. find the numbers

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. how many hours after the truck's departure will the two meet?