[tex]\bf \begin{array}{ccll} donuts&minutes\\ \cline{1-2} 30&60\\ 90&x \end{array}\implies \cfrac{30}{90}=\cfrac{60}{x}\implies \cfrac{1}{3}=\cfrac{60}{x}\implies x=180[/tex]
Answer: 180 minutes
Step-by-step explanation:
Cross multiply
90*60 = 5400
5400/30 = 180