Explain whether 0.9 x 10^-5 is written in scientific notation. If not, write the number correctly in scientific notation. Please help me

If a || b and b | y, then ? a) x || y. b) x | a. c) a | y. d) a || y.

Plz.yesterday, the snow was 2 feet deep in front of archie’s house. today, the snow depth dropped to 1.6 feet because the day is so warm. what is the percent change in the depth of the snow?

21 a stick 7 inches long is broken into two pieces, so that one piece is twice as long as the other one. how long are the two pieces?