What is the leangth of the second board?

Question

the board length is 2.5 meters long. The second shelf is 18cm longer then twice the leangh of the first shelf. The third shelf is 12cm shorter than the first shelf. The remaining shelf is 4cm longer than the first shelf if i have to use the entire board how long is the second shelve

Answer 1

We know the LEAST about the first shelf.

THAT is where you assign the variable:

 

First: X

Second: 2X + 18

Third: X - 12

4th:  X +4

 

The entire board is 2.5 meters long,

which is 250 cm

 

X + (2x +18) + (X-12) + (X+4)=  250

 

5x +10 = 250 <-- combines like terms

 

5x = 240

 

x = 48

 

THe first shelf is 48 cm

The 2nd shelf is 2*48 + 18 cm = 114

The 3rd shelf is 48 - 12 cm = 36 cm

The 4th shelf is 48 cm + 4 cm = 52 cm

 

The total is 48 + 114 + 36 +52  = 250 cm

which is 2.5 meters

Answer 2

f represents the length of the first shelf

2f + 18 represents the length of the second self

f - 12 represents the length of the third shelf

f + 4 represents the length of the fourth self

 

f + 2f + 18 + f - 12 + f + 4 = 2.5

 

Can you solve for f and answer?