Mrs Devi had 2.5 m of ribbon at first. She used 8 cm of it.

1. Convert the length used from cm to m

$8 \text{ cm} = 8 \div 100 \text{ m} = 0.08 \text{ m}$

2. Subtract the used length from the initial length to find the remaining length

$2.5 \text{ m} - 0.08 \text{ m} = 2.42 \text{ m}$

1. Convert the remaining length from part (a) into centimetres

Remaining length $= 2.42 \text{ m} = 242 \text{ cm}$

2. Divide the remaining length by 2 to find the length of each piece

$242 \div 2 = 121 \text{ cm}$