11.5 * 2.3 = large door size
large door size / 12 = large door size in feet
large door size in feet / 10 = how many large doors can be cut from the board. (you have to round it down if there's a decimal- no 1/2 doors.)
When multiplying terms that have the same base (in this case, 
) but different exponents, you can add their exponents to make them one term.
In this case, we can add the exponents of :
A simplified version is 
.
Answer:
17 years
Step-by-step explanation:
The compound interest formula is ...
A = P(1 +r/n)^(nt)
where P is the principal invested at annual rate r, compounded n times per year for t years.
Filling in the numbers and solving for t, we find ...
16826.03 = 8534(1 +.04/12)^(12t)
16826.03/8534 = 1.0033333...^(12t)
Taking logs, we have ...
log(16826.03/8534) = 12t·log(1.0333333...)
Dividing by the coefficient of t gives ...
log(16826.03/8534)/(12·log(301/300)) = t ≈ 17.000
It will take 17 years for the account balance to reach $16,826.03.
40 = n-.40n
40 =n(1-.4)
40 = n(.6
divide by .6 on each side
40/.6 =n
n=66 2/3
