# math

posted by
**bill**
.

Ken's average driving speed is 25km/hr faster than Jim's. In the same length of time it takes Ken to drive 279 km, Jim drives only 204 km. What is Ken's average speed?

Possible Answers:

a) 93 km/hr

b) 118 km/hr

c) 43 km/hr

d) 68 km/hr

Let x equal the speed of Jim's car.

279/x + 25 = 204/x

204x + 5100 = 279x

5100 = 75x

5100/75 = 75/75x

x = 68km/h

Therefore the avg. speed of Jim's car is 68km/h. Since Ken's car is 25km/h faster...68+25 = 93km/h.

Therefore the avg. speed of Ken's car is 93 km/h.