We must build the proportion
deliveries made : deliveries due = x : 100
in fact, we must express the fraction of work done as a fraction with denominator 100.
So, we have
[tex]\dfrac{36}{80}=\dfrac{x}{100}\iff x=\dfrac{3600}{80}=45[/tex]
Trey has completed 45% of his work so far.
