[tex]525\left(1-e^{-0.038t}\right)=300\\\\525-525e^{-0.038t}=300\\\\-525e^{-0.038t}=300-525\\\\-525e^{-0.038t}=-225\\\\e^{-0.038t}=\dfrac{225}{525}\\\\
e^{-0.038t}=\dfrac{3}{7}\\\\-0.038t=\ln\left(\dfrac{3}{7}\right)\\\\\boxed{t=-\ln\left(\dfrac{3}{7}\right)\times0.038}
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