Step-by-step explanation:
Sn=n/2(2a+(n-1)d)
910=n/2{2a+(n-1)d}
1820=n{2a+(n-1)d}
1820=20{2a+(20-1)d}
1820=20{2a+19d}
91=2a+19d
An=a+(n-1)d
95=a+(20-1)d
95=a+19d
91=2a+19d
---------------
4=-a
a=-4
91=2a+19d
91=2(-4)+19d
91=-8+19d
91+8=19d
99=19d
d=99/19
A=-4
"Note how for each (x,y) pair of points given we see that x*y = 60
For instance, the point (4,15) has x = 4 and y = 15 so x*y = 4*15 = 60
Another example: (x,y) = (6,10) means x = 6 and y = 10, so x*y = 6*10 = 60
The fact that this is true for ALL of the points shown indicates we have an inverse variation of the form x*y = k where k = 60 in this case.
Therefore, the answer is B.) An inverse function is the best model because the products of corresponding x- and y-values are equal."
Answer:
25x - 45 = 5(5x - 9)
Step-by-step explanation:
Find the greatest common factor (GCF) of 25 and 45.
You can do this several ways, but one way is to list all the factors of both numbers and find the greatest common one:
Factors of 25: 1, 5, 25
Factors of 45: 1, 3, 5, 9, 15, 45
Therefore, 25 and 45 have 2 common factors: 1 and 5
So the greatest common factors is 5
25x - 45 = 5(ax - b)
To find the value of a, simply divide 25 by 5: 25 ÷ 5 = 5
To find the value of b, divide 45 by 5: 45 ÷ 5 = 9
25x - 45 = 5(5x - 9)
Answer:
All three statements are true
Step-by-step explanation:
A shipping fee of 5% is charged online with every item purchased online
First let's just take each option and calculate them based on this, to see if the answers matched
Keith buys a 40 dollar book
40 x 0.05 = 2
Therefore there will be a two dollar fee on Keith's book
40 + 2 =42
The first statement is true
A chair costs $80
80 x 0.05 = 4
80 + 4 = 84
The second statement is true
George buys a 20 dollar calculator
20 x 0.05 = 1
20 + 1 = 21
The third statements are true
All three statements are true
Answer : 70
Step-by-step explanation: because 40 +30 and the biggest number in the chart is 7 just add a 0 and it becomes 70
