m=-5/6,(3,4)

I think they are asking how to find the slope between (5,6) and (3,4)....easy......

Subtract the y's    6-4 = 2

Subtract the x's in the same order as you subtracted the y's ...  5-3 = 2

Put the first result over the second....2/2  = 1.....and there's the slope!!!

Do you mean m=-5/6*(3*4)?  If so m = -10

I think that they mean what line has a gradient of -5/6 and goes through (3,4)

$$\frac{y-4}{x-3}=\frac{-5}{6}\\\\
y-4=\frac{-5}{6}\times (x-3)$$

you can finish it!