This problem involves creating a system of equations to determine how many tubes of food A and food B are required to meet nutritional requirements.

Given information:

1. Food A:

   • 4 units of protein
   • 2 units of carbohydrates
   • 2 units of fat
   • Weight: 2 pounds

2. Food B:

   • 3 units of protein
   • 6 units of carbohydrates
   • 1 unit of fat
   • Weight: 3 pounds

Nutritional Requirements:

• 48 units of protein
• 42 units of carbohydrates
• 20 units of fat

We need to find the number of tubes of food A (denoted as $x$) and food B (denoted as $y$) that meet these nutritional requirements.

Formulating the system of equations:

From the given information, we can set up the following three equations based on protein, carbohydrates, and fat content:

1. Protein: $4x + 3y = 48$
2. Carbohydrates: $2x + 6y = 42$
3. Fat: $2x + 1y = 20$

Now, I'll solve this system of equations.It seems that the system of equations has no solution in its current form. This could indicate an inconsistency in the provided nutritional information or a mistake in the formulation of the problem.

Let's double-check the formulation of the system and the values. Would you like me to review the problem conditions again or assist with another approach to solving it?