Answer:

Step-by-step explanation:
let the number be n , then
4 - 4n = 2n ( add 4n to both sides )
4 = 6n ( divide both sides by 6 )
= n
The number is 
28 divided by 4= 7
7-3=4
answer: 4 notebooks left.
Answer:
Sarah has to invest $502,958.58 today.
Step-by-step explanation:
This is a simple interest problem.
The simple interest formula is given by:
In which E is the amount of interest earned, P is the principal(the initial amount of money), I is the interest rate(yearly, as a decimal) and t is the time.
After t years, the total amount of money is:
In this question:

She has to invest P today.

So



Sarah has to invest $502,958.58 today.
Answer:
30
Step-by-step explanation:
since the 2 sides are congruent, the two angles are congruent, so
75+75+ x= 180
150+x=180
x=30