Halp me plz im gonna lose all video game 4 2 week guys i gunna be deprezzed

okay here is problem

Which equation would demonstrate the associative property?

A) (3·4) + (3·5) = 3(4+5)
B) 3·5=5·3
C) (3·4)·5=3·(4·5)
D)

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?

Three numbers x, y, and z are in the ratio 2: 7: 8. if 12 is subtracted from y, then three numbers form a geometric sequence (in the order x, y–12, z). find x, y, and z. there are 2 sets.

On #16 : explain how factoring a trinomial, ax^2+ bx+ c, when a does not equal 1 different from factoring a trinomial when a = 1.