Answer:
205
Step-by-step explanation:
Given
N(t) = 100 + 15t is the equation of the relation.
We're asked to find N(7)
Taking a look at the question again and putting it side by side the equation
N(t)
N(7)
We can deduce that t = 7, and as such, solve for it in the equation given
N(7) = 100 + 15(7)
N(7) = 100 + 105
N(7) = 205
Therefore, the number of unread mails after 7 days will be 205
The simplified expression of 
is 
<h3>How to simplify the expression?</h3>
The expression is given as:
Divide 162 and 2 by 2
Take the square root of 81
Apply the quotient rule of indices
Evaluate the difference
Take the square root of x^18
Hence, the simplified expression of is
Read more about expressions at:
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4x , 6y
I think
Sorry if it’s not right
(1) 3x+2y=12
(2) -4x+6y=24
Solving the system of equations using the method of substitution:
Isolating y in the first equation:
(1) 3x+2y=12→3x+2y-3x=12-3x→2y=12-3x→2y/2=(12-3x)/2→y=(12-3x)/2
Replacing "y" by (12-3x)/2 in the second equation:
(2) -4x+6y=24
y=(12-3x)/2→-4x+6[(12-3x)/2]=24
Solving for x:
-4x+3(12-3x)=24
-4x+36-9x=24
-13x+36=24
-13x+36-36=24-36
-13x=-12
-13x/(-13)=-12/(-13)
x=12/13
Replacing "x" by 12/13 in y=(12-3x)/2
x=12/13→y=[12-3(12/13)]/2
y=(12-36/13)/2
y={[(13)(12)-36]/13}/2
y=[(156-36)/13]/2
y=(120/13)/2
y=(120/13)(1/2)
y=60/13
x=12/13; y=60/13
-x+2y=-12/13+2(60/13)
-x+2y=-12/13+120/13
-x+2y=(-12+120)/13
-x+2y=108/13
Answer: The value of -x+2y is 108/13
