Answer:
12
Step-by-step explanation:
The first cave has 7 times more bats than the last cave. So if the 45th cave has b bats, then the first cave has 7b bats.
There are 77 bats in every row of 7 caves. So if there are 7b bats in the first cave, then there are 77−7b bats in caves 2 through 7.
Since there are also 77 bats in caves 2 through 8, that means cave #8 must have 7b bats. Repeating this logic:
#1 = 7b
#2-#7 = 77−7b
#8 = 7b
#9-#14 = 77−7b
#15 = 7b
#16-21 = 77−7b
#22 = 7b
#23-28 = 77−7b
#29 = 7b
So the first 29 caves have 5(7b) + 4(77−7b) = 308 + 7b bats.
Now we do the same thing from the other end. If cave #45 has b bats, then caves #39-#44 have 77−b bats. And since caves #38-44 have 77 bats, then cave #38 has b bats. Therefore:
#45 = b
#39-44 = 77−b
#38 = b
#32-37 = 77−b
#31 = b
So caves 31 through 45 have 3b + 2(77−b) = 154 + b bats.
Adding that to the first 29 caves, plus x number of bats in cave #30:
308 + 7b + x + 154 + b = 462 + 8b + x
We know this equals 490.
490 = 462 + 8b + x
28 = 8b + x
x is a maximum when b is a minimum, which is b = 2.
28 = 8(2) + x
x = 12
There are at most 12 bats in the 30th cave.
Answer:16
Step-by-step explanation:
Let the number be X
Twice the sum of a number and 5
= 2X+5
Three times the difference of the number and 2
= 3(X - 2)
Since Twice the sum of X and 5 is equal to three times the difference of the X and 2, This means
2(X + 5 )= 3(X - 2)
2X +10 = 3X - 6
3X -2X = 10 + 6 = 16
X = 16
Check
2×(16+5) =3×(16-2)
2×21 = 3×14
42 = 42
Answer:
Step-by-step explanation:
Let b= number of people per bus
10b + 5 > 450
10b > 445
b > 44.5
Minimum per bus is 45 students
Answer:
A
Step-by-step explanation:
62 because 90 minus 15, minus 13, is equal to 62
