Lines p and q are perpendicular. if the slope of line p is 2, what is the slope of line q

Solution here,

Slope of line p(m1)=2

Slope of line q(m2)=?

Since they are perpendicular,

m1m2=-1

or, 2×m2=-1

or, m2=-1/2

it is a. 4.2 because 7.6-3.4 gets the remaining length of 4.2. i might be wrong but i am pretty sure this is the answer.