wj0126_9 said:

y-(9)=7/8 (x-(2))

y+9=7/8 (x-2)

y+9=7/8x + 16/8 + -9/1*8/8 =72/8

Okay, with given coordinates (2, 9), you've got an equation for the line.

y - 9 = 7/8 * (x - 2)

Now, if you've been asked to put this into Slope-Intercept form, then solve for y.

We don't change y - 9 into y + 9 (I'm not sure why you did that).

On the other side, we distribute 7/8 across the difference x - 2 using the Distributive Property.

\(\displaystyle y \;-\; 9 \;=\; \frac{7}{8} \cdot x \;-\; \frac{7}{8} \cdot \frac{2}{1}\)

Can you multiply 7/8 times 2, to simplify that product? Then add 9 to both sides of the equation.

BTW: What are the instructions for this exercise?