keeping in mind that 70% of anything is 70/100 * anything, thus
[tex]\bf \begin{array}{ccll}
\stackrel{percentage}{points}&\stackrel{test}{completed}\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
45&1\\\\
x&\frac{70}{100}
\end{array}\implies \cfrac{45}{x}=\cfrac{1}{\frac{70}{100}}\implies \cfrac{45}{x}=\cfrac{\frac{1}{1}}{\frac{7}{10}}
\\\\\\
\cfrac{45}{x}=\cfrac{1}{1}\cdot \cfrac{10}{7}\implies \cfrac{45}{x}=\cfrac{10}{7}\implies \cfrac{45}{x}=\cfrac{10}{7}\implies \cfrac{45\cdot 7}{10}=x
\\\\\\
\cfrac{63}{2}=x\implies \boxed{31.5=x}[/tex]
so, you get that many percentage points, now... add that to 51.32.
