Simplify the expression 2/5y - 4 + 7 - 9/10y

Timed*** there are 8 rows and 8 columns, or 64 squares on a chessboard. suppose you place 1 penny on row 1 column a, 2 pennies on row 1 column b, 4 pennies on row 1 column c, and so on … how many pennies are on each square? a =   b =   c = d =   e =   f = g =   h =

If a =6, what is the value of 2a(3b + 5c)?

Suppose the first five terms of a sequence are 4, 5, 9, 27, 123. how could the next term in the sequence be generated?