To find out how long it will take Mr. Holloway to make 7 guitars, we first need to determine his rate of production based on the information provided.
He took 8 weeks to make 2 guitars. Therefore, we can calculate the time it takes him to make one guitar:
\[ \text{Time per guitar} = \frac{\text{Total time}}{\text{Number of guitars}} = \frac{8 \text{ weeks}}{2 \text{ guitars}} = 4 \text{ weeks per guitar} \]
Now, we can calculate the total time it will take to make 7 guitars by multiplying the time taken per guitar by the number of guitars:
\[ \text{Total time for 7 guitars} = \text{Time per guitar} \times \text{Number of guitars} = 4 \text{ weeks per guitar} \times 7 \text{ guitars} = 28 \text{ weeks} \]
Therefore, it will take Mr. Holloway 28 weeks to make 7 guitars.