Pls help me find measure b I will give brainlest

Atype of plant is introduced into an ecosystem and quickly begins to take over. a scientist counts the number of plants after mmonths and develops the equation p(m)= 19.3(1.089)^m to model the situation. most recently, the scientist counted 138 plants.assuming there are no limiting factors to the growth of the plants, about how many months have passed since the plants werefirst introduced? a)o 6.1b)0.6.6c)10 72d)o 23.1

Need so much on this one how many yards?

Can someone me with my math problems i have a bunch. i will give brainliest and lots of pleeeaaasssee