23. A board for a shelf is 2.31 m long and 33.4 cm wide. to. What is the area of ​​the shelf in square meters? b. What is the perimeter of the shelf in centimeters? c. Which will reduce the area of ​​the shelf more: (1) cutting 3.4 cm from its width, or (2) cutting 0.31 m from its length?

1 m = 100 cmso 2.5 m = (2.5 * 100) = 250 cm

a = 1st shelf

b = 2nd

c = 3rd

d = 4th

a + b + c + d = 250

b = 2a + 18

c = a - 12

d = a + 4

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

5a + 10 = 250

5a = 250 - 10

5a = 240

a = 240/5

a = 48 cm <== 1st shelf

b = 2a + 18 = 2(48) + 18 = 114 cm <== 2nd shelf

c = a - 12 = 48 - 12 = 36 cm <== 3rd shelf

d = a + 4 = 48 + 4 = 52 cm <== 4th shelf

so 2nd shelf is 114 cm