Erica and Amy started biking in the opposite directions at the same time from the same place. Erica biked at a speed of 6 meters per second and Amy biked at a speed of 4 meters per second. How soon were they exactly 1 km apart?

Answer:100 secondsErica and Amy are at distance of 1 km in 100 secondsStep-by-step explanation:They both are travelling in opposite directions so the sum of the distances they travel is the distance between them.Let's take t as the total time taken to achieve a seperation of 1kmDistance traveled by Erica , (Speed of Erica - v1)x1 = v1 * tDistance travelled by Amy , (Speed of Amy - v2)x2 = v2*tTherefore sum of the distances they traveled is x1+x2 = xx = v1*t + v2*tx = t*(v1 + v2)Here it is given that final seperation between Amy and Erica is 1km or 1000 mTherefore x = 1000 mThus t = [tex]\frac{x}{v1+v2}[/tex]Substituting given values v1 = 6 m/s v2 = 4 m/sTherefore,They are apart by exactly 1km in a time of 100 sec