Synthetic fibers are made from raw materials such as petroleum, based on chemicals or petrochemicals [20]. These materials are polymerized into a long, linear chemical with different chemical compounds and are used to produce various types of fibers.
he increase from 125cm to 135cm
first step :

second step :
percents he change is

Henry has completed 40% of his work, leaving him with a remaining 60%.
What you do is divide 20 by 50 and your answer is .4, move the decimal two places to the right to get your percent, 40. Then subtract it out of 100 and you get the remaining 60%, which essentially is your answer.
The 1, 2, 3 I’m not sure bout the 4th one