documentclass{article}
usepackage[fleqn]{amsmath}
renewcommand{familydefault}{sfdefault} % optional
usepackage{enumitem}
setlist[enumerate,1]{label=textbf{arabic*}}
setlist[enumerate,2]{label=textbf{(alph*)}}

begin{document}

begin{enumerate}[start=7]
item
begin{enumerate}
item By writing $sec x =(cos x)^{-1}$, use the chain rule dots
    [
    frac{mathrm{d}y}{mathrm{d}x}=sec xtan x
    ]
    hfill{bfseries[2 marks]}
item The function $f$ is defined by
    [
    f(x)=2tan x-3sec x,quadtext{for}quad 0<x<frac{pi}{2}
    ]
    Find the value of the $y$-coordinate of the stationary point
    of the graph of $y=f(x)$, giving dots
    parhfill{bfseries[6 marks]}
end{enumerate}
end{enumerate}
end{document}