Farmer Yumi has too many plants in her garden. If she starts out with 150 plants and is losing them

Farmer Yumi has too many plants in her garden. If she starts out with 150 plants and is losing them at a rate of 4% each day, how long will it take for her to have 20 plants left? Round UP to the nearest day.

We set up the function P(d) where d is the number of days sine she started losing plants:
P(d) = Initial plants * (1 - Loss percent / 100)^d

Plugging in our numbers, we get:
20 = 150 * (1 - 4/100)^d
20 = 150 * (1 - 0.04)^d

Read left to right so it's easier to read:
150 * 0.96^d = 20

Divide each side by 150, and we get:
0.96^d = 0.13333333333

To solve this logarithmic equation for d, we type it in our search engine and we get:
d = 49.35

The problem tells us to round up, so we round up to 50 days