Please help me with these 3 questions!! Will mark Brainliest :)

Can some one me with these questions

At noon a tank contained 10cm water. after several hours it contained 7cm of water. what is the percent decrease of water in the tank?

Does the construction demonstrate how to copy an angle correctly using technology a) yes the distance between points a and f was used to create circle h b) yes the distance between points f and g was used to create circle h c) no the distance between points a and f was used to create circle h d) no the distance between points f and g was used to create circle h