Answer:
30 * t
Explanation:
The garden club earned $15 per hour by weeding neighborhood gardens for t hours.
A generous donor has agreed to double their earnings.
Double their earnings means we multiply by 2
So earning 15 per hour becomes 2*15 = 30 per hour
Given the number of hours is t
Earnings = $30 times number of hours
Earnings = 30 * t