Simple just subtract and u get-74.85
Answer:
The interest rate for the given investment is 18%.
Step-by-step explanation:
We are given that,
The function representing the investment model is,
.
It is required to find the interest rate for the investment.
Since, the function can be re-written as,

i.e. 
So, on comparing with the formula for compound interest i.e.
, where 'r' is the interest rate.
We have that,
The interest rate for the given investment is 0.18 i.e. 18%.
We are given equation :




Therefore, final factored form it

We can't factor it more.
Therefore,
x+1=0.
x=-1.
Therefore, the real solution of the equation would be -1.