Sn=n/2 (2a1 +(n-1)d)
[s5= 5/2 (2a1 +(5-1)d) = 5a1+10d]
s6=3(2a1+5d) = 6a1+15d
s4=2(2a1+3d) = 4a1+6d
6a1+15d -(4a1+6d) = 5 -----(1)
s7=7/2(2a1+6d) =7a1+21d
6a1+15d + 7a1+21d = 21 -----(2)
(1) 2a1+9d=5 -----(3)
(2) 13a1+36d=21 ----(4)
(3)*4 ; 8a1+36d=20 ----(5)
(4)-(5) 5a1 = 1
so a1 = 1/5
(3) 2a1+9d=5
2(1/5)+9d = 5
9d = 5-2/5 =23/5
d = 23/45
so [s5= 5/2 (2a1 +(5-1)d) = 5a1+10d = 5(1/5) + 10(23/45) = 1 + 5.11 = 6.11 ]
i'm not sure about the answer but the process is correct
<span>So there are 4 books
=> 1 physics
=> 1 chemistry
=> mathematics
=> Biology
These books needs to be place on a shelf.
Now, let’s find the probability of mathematics book to be placed on top.
Let’s analyze the problem
Probability => 1 mathematics book / 4 total books
P = Probability
P = 1 / 4
P = ¼ or 0.25
Thus, the probability of mathematics book to be placed on top inside the shelf
approximately is ¼ or 0.25.</span>
Alright so one dozen cookies is 12 cookies. So 40 dozen cookies is 480 cookies (40x12). If there’s 157 students then u divide 480 by 157 which gets u 3.06 cookies per person
Answer:
y=3
Step-by-step explanation:
3x-12= 3x + 7
+12 +12
3x = 3x + 19
-3x -3x
x = 19