How do you solve:?

Question

Book B is twice as long as Book A.
Book C is 30 pages longer than Book B.
Together the books have 280 pages.
How long is book C?
How do i solve this to get the answer to be 130?
Please show me step by step.

Answer 1

5A+30=280

5A=250

A=50

C=2A+30=130

I was always known to "leave out steps" by my math teachers. These are more than enough steps.

Answer 2

First state your facts:[b = Book B; a = Book a; c = Book c]
b = 2a
c = 30 + b
a + b + c = 280

The fist thing you can substitute:
a + b + c = 280
a + 2a + [30 + 2a] = 280

So i will explain each part of this equation.
a = a [obviously]

2a = b
This is because Book B is twice as long as Book A.

30 + 2a = c
Because c = 30 + b AND b = 2a. So you substitute b for 2a, which leads to 30 + 2a = c.

Back to the equation:
a + 2a + 30 + 2a = 280
~add common terms~
5a + 30 = 280
5a + 30 - 30 = 280 - 30
5a = 250
5a/5 = 250/5
a = 50

Now that we know what a equals- we can go back to one of the equations on top. In this case we use c = 30 + 2a. This is because the question only asks for how long book c is.

c = 30 + 2a
c = 30 + 2*50
c = 30 + 100
c = 130

And that is how you get the answer of 130.

Hope that helped you :]

Answer 3

This is a system of equations type question.
From your statements, I can come to these equations:

B=2A
C=B+30
A+B+C=280

Simple enough, right?

Notice, first two equations have only two terms. The last one has three terms. Usually, with these setup, you'll have to eliminate one term by combining equations.

I see, by combining two equations, I can get rid of either A or B. I choose B. You'll need C for the final answer, so keep it.

Let's combine first and second...
B=2A and C=B+30.... also C-30=B right?
Then C-30 = 2A, then
C-2A=30... now B is gone!

Now, let's combine first and third...
B=2A and A+B+C=280
Then A + 2A + C = 280
3A + C = 280... B is also gone!

Now, we have two equations made out of 3 and we also got rid of B as a variable. We only need to concern ourselves with C and A.

C-2A=30
3A + C = 280

I'm going to rewrite the first one as C=30+2A
Substitute this into the second
3A + 30 + 2A = 280
5A + 30 = 280
5A = 280 - 30
5A = 250
A = 50

Now we know what A is....
use this equation: C-2A=30 and substitute A=50
C-2(50)=30
C-100=30
C=130

Viola!

Answer 4

you are correctl
let length = x
set up an equation

x + 2x+2x+30 = 280
5x+ 30 = 280
5x= 250
x = 50 pages = book A
Book B = 100 Pages
and book C = 100+ 30 = 130 pages

Answer 5

B= 2A
C=B+30
therefore:
C=2A+30

Now, add A B and C together, we end up with A+2A+2A+30=280
-30 from each side: 5A=250

divide by 5: A=50

replace "A" with "50" in our formula: C=2(50)+30

2*50=100

100+30=130.

Final answer: C=130.

there you have it.

Answer 6

let pages of book A = x
so book B = 2x
and book C = (2x+30)

acc. to ques,

pages of book A + pages of book B + pages of book C=280
x + 2x + (2x+30) = 280
5x = 280-30
5x = 250
x=50

so pages of book C = (2 * 50) + 30
=100+30
=130
proved!!

Answer 7

try to go to this sites:
http://www.purplemath.com
http://www.helpalgebra.com
http://www.freemathhelp.com/algebra-help...
http://education.yahoo.com/

Hope it help...!!!