Problem: How does the sentence end?

Climbing a  tree was tough for Michael but easy for Justin because 
Answer: Justin had stronger legs.

Problem: How does the sentence end?

Although Elena was a worse lawyer than Sarah, 
Answer: Sarah was unable to connect with their clients emotional problems.

Problem: How does the sentence end?

Monica needed help from Erin understanding the benefits because 
Answer: Monica had only skimmed the insurance plan.

Problem: How does the sentence end?

The serum Betty was using doesn't work as well as Amy's because 
Answer:
Betty shopped at a discount store.