I presume you know what the differential of the sine function is. Is that correct?

Now you use a substitution and the chain rule.

$y = 12.5sin(0.06t).$

$u = 0.06t \implies \dfrac{du}{dx} = what?$

$Also\ u = 0.06t \implies y = 12.5sin(u) \implies \dfrac{dy}{du} = what?$

How do you calculate $\dfrac{dy}{dx}$ knowing $\dfrac{du}{dx}$ and $\dfrac{dy}{du}$?