Starting Log and Ln Chapter 4 (Need Help)

Hello,

In class I am breifing chapter 4 through 4.5 then we are jumping to 9 so I have to get 4 down quickly. In my homework are two questions I'm getting fustrated on. The first should be simple since its basically substituiting for variables. The second delts with the relationship between ln and to the power variable "e". Any help would be much appreciated as I have typed out the questions in full below, thanks!

__Question on Chapter 4__

use formula below

M=Lrk/12(k-1) where k=(1+r/12) *to the power of * 12t

and t is the number of years that loan is in effect

Some lending institutions calculate the monthly payment M on a loan of L dollars at an interest rate r (expressed as a decimal) by using the formula

a) Find the monthly payment on a 30–year $90,000 mortgage if the interest rate is 7%

b) Find the total interest paid on the loan in (a).

c) Find the largest 25–year home mortgage that can be obtained at an interest rate of 8% if the monthly payment is to be $800.

__Question on LOG and LN__

The Jenss model is generally regarded as the most accurate formula for predicting the height of preschool children. If y is the height in cm and x is the age in years, then

y=79.041 + 6.39x-e *to the power of * 3.261-0.993x

for **1/4 ** (less than or eual to) **x ** (less than or equal to **6) ** years.

What is the height of a typical two year old?