J has read 160 pages in a book. This is 4/5 of the entire book. How many pages does the book have?
Let x be the number of pages in the book.
We know that 4/5 of the book's entire length is 160 pages, so 4/5 * x = 160.
Multiplying both sides of the equation by 5/4, we get x = 200 pages.
Therefore, the book has 200 pages. Answer: \boxed{200}.
S is twice as old as B. In 5 years, the sum of their ages will be 25 years. Find their present ages.
Let's assume B's present age is x.
Therefore, S's present age is 2x, as S is twice as old as B.
In 5 years, B's age will be x + 5, and S's age will be 2x + 5.
According to the problem, the sum of their ages in 5 years will be 25 years.
So, we have the equation x + 5 + 2x + 5 = 25.
Combining like terms, we get 3x + 10 = 25.
Subtracting 10 from both sides of the equation, we get 3x = 15.
Dividing both sides of the equation by 3, we get x = 5.
So, B's present age is x = 5 years.
And S's present age is 2x = 2 * 5 = 10 years.
Therefore, B is 5 years old and S is 10 years old. Answer: \boxed{5, 10}.
A rectangle is 15 cm wide. Find the area and perimeter of the rectangle if it’s width is 3/5 of its length.
Let's assume the length of the rectangle is x cm.
Given that the width is 3/5 of the length, we have the equation:
Width = 3/5 * Length
15cm = 3/5 * x
Multiplying both sides of the equation by 5/3, we get:
x = 15cm * 5/3
x = 25cm
So, the length of the rectangle is 25 cm.
The area of a rectangle is given by the formula A = length * width.
Therefore, the area of the rectangle is:
A = 25cm * 15cm
A = 375 cm^2
The perimeter of a rectangle is given by the formula P = 2 * (length + width).
Therefore, the perimeter of the rectangle is:
P = 2 * (25 cm + 15 cm)
P = 2 * 40 cm
P = 80 cm
Therefore, the area of the rectangle is 375 cm^2 and the perimeter is 80 cm. Answer: \boxed{375 \, \text{cm}^2, 80 \, \text{cm}}.
To find the total number of pages in the book, we need to divide the number of pages read (160) by the fraction of the book read (4/5).
Let's set up an equation to solve for the total number of pages (P):
160 = (4/5) * P
To isolate P, we can multiply both sides of the equation by 5/4:
160 * (5/4) = P
Simplifying:
200 = P
Therefore, the book has a total of 200 pages.
To find the total number of pages in the book, we can use the information given that J has read 4/5 of the book, which is equivalent to 160 pages.
Let's set up an equation to represent this situation. Let x represent the total number of pages in the book:
4/5 * x = 160
To solve for x, we need to isolate it on one side of the equation. We can do this by multiplying both sides of the equation by the reciprocal of 4/5, which is 5/4:
(4/5 * x) * (5/4) = 160 * (5/4)
x = 800/4
x = 200
Therefore, the book has a total of 200 pages.