Answer
No, it is not.
Work Step by Step
In order to see if something is a solution to an equation, we plug in the (x,y) point to see if the equality is correct. Thus, we plug (3.5,6.8) into y=-1.2x-2.6 to find:
6.8=-1.2(3.5)-2.6
6.8=-6.8
6.8 does not equal -6.8, so this is not a solution to the equation.