A salesman sold twice as much pears in the afternoon than in the morning. If he sold $510 kilograms of pears that day, how many kilograms did he sell in the afternoon? Choose one:
A) 120  B) 180  C) 340  D) 280  E) 320

Rationale: "3 x = 510 x = 170 therefore , the salesman sold 170 kg in the morning and 2 ⋅ 170 = 340 kg in the afternoon . so answer is c ."
Answer: C