I am given $v=6-4x$ where $v$ is velocity and $x$ is position of the body. I am now asked to find displacement between $t=1.4$, distance covered from $t=1.4$, average velocity from $t=2.5$, average acceleration, etc. I am not able to find an approach to these kind of problems where $v$ is not given in terms of $t$, or say, it is given like $v=kt^2$ or like $v=kx$. How should I start these kind of problems and develop a thinking for these? Please help me.