Answer:
The expressions for the payment made to Mary are,
(Monday) 90 = 15m + b
(Tuesday) 62 = 8m + b
where m and b are the fee per student and the base fee, respectively. Solving for m and b, the values are 4 and 30.
The equation that represents Mary's earning is
y = 4x + 30
For 20 students,
y = 4(20) + 30 = 110
For Lisa's earnings,
y = 8x + 15
Substituting 20,
y =8(20) + 15 = 175
Thus, Lisa would earn more than Mary by $65.
(Btw this is not my work, I got it from someone else on brainly and wanted to help lol)
There shouldn't be a negative in front of one of the equations.
Answer:
S'(x)=-0.006x2+0.8x+9
Step-by-step explanation:
The rate of change of the sales S(x) with respect to the amount of money spent on advertising x is then the derivative of S(x) with respect to x. What we have to calculate is S'(x).
We know that the derivative of 
is 
(where a is a constant), and the derivative of a sum is the sum of the derivatives, so we can calculate the derivative of each term independently:
S'(x)=(−0.002x3 + 0.4x2 + 9x + 500)'=(−0.002)(3)x2 + (0.4)(2)x + 9
Which means:
S'(x)=-0.006x2+0.8x+9
The explicit formula for this geometric sequence 81, 27, 9, 3, … is aₙ = 81(1/3)ⁿ⁻¹. It has common ratio of 1/3 and first term of 81.
<h3>What is an
equation?</h3>
An equation is an expression that shows the relationship between two or more variables and numbers.
A geometric sequence is in the form aₙ = ar⁽ⁿ⁻¹⁾, where a is the first term and r is the common ratio.
The geometric sequence 81, 27, 9, 3, … has common ratio:
r = 27/81 = 1/3
The explicit formula for this geometric sequence 81, 27, 9, 3, … is aₙ = 81(1/3)ⁿ⁻¹. It has common ratio of 1/3 and first term of 81.
Find out more on equation at: brainly.com/question/2972832
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Answer:
64percents
Step-by-step explanation:
25-9=16 grams - weight of copper
(16/25)*100=64 percents
