A large field of 700 hectares is divided into two parts. The difference of the areas of the two parts is one-fifth of the average of the two areas. What is the area of the smaller part in hectares?  Choose the correct option:
A) 310  B) 320  C) 305  D) 315  E) 325
Average of the two areas =7002=350   one-fifth of the average of the two areas=3505=70   ⇒ Difference of the two areas =70   Let area of the smaller part =x hectares.   Then, area of the larger part =x+70 hectares.   x+(x+70)=700⇒2x=630⇒x=315   Answer is 315.
<result>D</result>
A large field of 700 hectares is divided into two parts. The difference of the areas of the two parts is one-fifth of the average of the two areas. What is the area of the smaller part in hectares?