Final answer:
The patients who are able to donate blood are the 15-year-old at 135 lb and the 20-year-old at 105 lb. They meet the age and weight requirements set by the American Red Cross.
Step-by-step explanation:
To determine which patient is able to donate blood, we need to consider their age and weight. According to the information provided, the following patients can donate blood:
- 15 y/o at 135 lb.
- 20 y/o at 105 lb.
The American Red Cross guidelines state that individuals must be at least 16 years old and weigh at least 110 pounds to donate blood. Both the 15-year-old who weighs 135 pounds and the 20-year-old who weighs 105 pounds meet these criteria and are eligible to donate blood.