We can use the sum of an aritmetic sequence
the sum from n=1 to n=r when the first term is a1 and the nth term is an is

first term is 1
last term is 100
there are 100 terms so n=100
so the sum is


S=5050
now you want us to divide by 10
5050/10=505
fun fact, gauss (famous math guy) did this when he was younger, legend has it that he was assigned this as an in class assigment to kill time but gauss found a neat pattern, he noticed that adding the end terms wer giving the same sum, example, 100+1=101, 2+99=101, etc, so he just needed to find al the pairs and add them all up
answer is 505
the result is 505
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)
Answer:
1. X = 17/A --- answer is (A)
2. (6, 0.7) (10, 1.9)
3. $10.99D + $9.99 ≤ $100
Step-by-step explanation:
1. AX + 4AX = 51 + 2AX
5AX = 51 + 2AX .... -2AX both side
3AX = 51 .. divide 3A
X = 17/A --- answer is (A)
2. 10y = 3x -11
(2, 0.5): 3*2 -11 = - 5 10y = 10*0.5 = 5 ..... not correct
(4, 1) 3*4 - 11 = 1 10y = 10*1 = 10 ....... not correct
(6, 0.7) 3*6 - 11 = 7 10y = 10*0.7 = 7 .....Correct
(8,2.3) 3*8 -11 = 13 10y = 10*2.3 =23 ..... not correct
(10, 1.9) 3*10 -11 = 19 10y = 10*1.9 = 19 .... correct
3. 1D cost $10.99
D piece cost: $10.99D
Shipping: $9.99
No more than $100: ≤ 100
D piece DVD + Shipping withtotal no more than $100:
$10.99D + $9.99 ≤ $100