The Change from Religious to Lay Teachers at Roman Catholic

The change from religious to lay teachers at Roman Catholic schools has been partly attributed to the decline in the number of women and men entering religious orders.The percent of teachers who are lay teachers is given by where t measured in decades, with corresponding to the beginning of 1960.
What percent of teachers were lay teachers at the beginning of 1990? Please round the answer to one decimal place.
__________ %
How fast was the percent of lay teachers changing at the beginning of 1990? Please round the answer to two decimal places.
__________ % / year
Find the year when the percent of lay teachers was increasing most rapidly.