Question

Please help, thanks in advance!

Answer 1

114 [cm].

Explanation:

1) if the length of the 1st shelf is 'x', then

2) the length of the 2d shelf is '2x+18', the 3d shelf is 'x-12' and the 4th shelf is 'x+4';

3) the sum of the all 4 shelves is 250 [cm], then it is possible to make up the equation:

x+(2x+18)+(x-12)+(x+4)=250;

4) the root of the equation above is x=48, then

5) the required length of the 2d shelf is 2*48+18=114 [cm].

Answer 2

Answer: 114

Explanation:

firstly, convert meters to centimeters:

2.5m * 100cm in a meter = 250 cm

let the length of the first shelf equal x:

250 = x + (2x + 18) + (x - 12) + (x + 4)

combine like terms:

250 = 5x + ( 18 - 12 + 4) = 5x +10

subtract 10 from both sides:

240 = 5x, then solve for x

240/5 = x

x = 48 cm

the length of the second shelf was 2x + 18, so plug in 48 for x:

2(48) + 18 = 114