To determine the number of different straight lines that can be formed by joining any two of the 12 points, where 7 of these points lie on the same straight line, we will follow a step-by-step approach:

1. Calculate the total number of lines formed by joining any two points out of 12 points: This can be done using the combination formula $\binom{n}{2}$, where $n$ is the number of points. For 12 points: $\binom{12}{2} = \frac{12!}{2!(12-2)!} = \frac{12 \times 11}{2 \times 1} = 66$

2. Subtract the lines formed only by the 7 collinear points: For the 7 collinear points, the number of lines formed by joining any two of these points is: $\binom{7}{2} = \frac{7!}{2!(7-2)!} = \frac{7 \times 6}{2 \times 1} = 21$ However, all 7 collinear points lie on the same line, so these 21 combinations correspond to only one line.

3. Account for lines formed by each pair of collinear points (already considered): We have already counted these lines as part of the total lines. We just need to recognize they represent only one unique line.

4. Total unique lines: Now, subtract the combinations of the 7 collinear points and add the unique line from these points: