Correct

合力

/ hélì / 
Strokes

Definition

to cooperate

Example

As a Verb

work collaboratively; work in conjunction (with); unite efforts; join forces; combine strength; pool efforts

1
Tāmen
他们
hélì
合力
jiāng
将
chē
车
cóng
从
nínìng
泥泞
zhōng
中
tuō
拖
le
了
chūlái
出来
  
。

Together they pulled the cart out from the mud.

2
Tóngxīnhélì
同心合力

work together with one mind; unite and make a concerted effort

As a Noun

resultant force