The total cost of the order is given as $31. Therefore, we can set up the equation as follows:
\[ 3c + 2.5p = 31 \]
Now, we also know from the problem that the total weight of the cashews and peanuts is 11 pounds. We can express this with another equation:
\[ c + p = 11 \]
Now we have a system of two equations:
- \( 3c + 2.5p = 31 \)
- \( c + p = 11 \)
We can solve this system to find the values of \( c \) (pounds of cashews) and \( p \) (pounds of peanuts).
From the second equation, we can solve for \( p \):
\[ p = 11 - c \]
Now, we can substitute \( p \) into the first equation:
\[ 3c + 2.5(11 - c) = 31 \]
Now, distribute the \( 2.5 \):
\[ 3c + 27.5 - 2.5c = 31 \]
Combine like terms:
\[ 0.5c + 27.5 = 31 \]
Now, isolate \( c \):
\[ 0.5c = 31 - 27.5 \] \[ 0.5c = 3.5 \] \[ c = \frac{3.5}{0.5} \] \[ c = 7 \]
Now that we know \( c = 7 \), we can find \( p \):
\[ p = 11 - c = 11 - 7 = 4 \]
So, the order consists of:
- 7 pounds of cashews
- 4 pounds of peanuts