One train is at the 20 Km position, another is at the 200Km position, both are approaching, the first with a speed of 30Kmh-1 and the second with a speed of 48 Kmh-1. If they leave at 7:12, what time do they cross? t = 2.30 H Time: 9:30 am.

Explanation:

The distance between them is 200 km − 20 km = 180 km.

The relative velocity is 30 km/h − (-48 km/h) = 78 km/h.

The time it takes is 180 km / (78 km/h) = 2.31 hours, or 2 hrs 18 min.

Therefore, the trains meet at 9:30 AM.

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y