Which of the following is an example of a closed system? A estuary where fresh and ocean water mix
A chemical reaction within deep ocean organisms allowing them to glow
A living single-celled organism such as a phytoplankton
A river that flows into the ocean

Phillip had some bricks. he stacked them in 6 equal piles. which expression shows the number of bricks phillip put in each pile? let the variable m stand for the unknown number of bricks. m + 6 m÷6    m−6    6m

Is it greater than or less than7*3_9*2

Add, subtract, multiply, or divide as indicated. list any restrictions for the variable(s) and simplify the answers when possible. 1) x-2 / x+5 + 3x / 2x-1 2) x+6 / x-6 - x^2 / x+6 3) x+9 / x-4 + x+2 / x^2-11x+28 4) x / x^2-64 + 11 / 2x^2+11x-40 5) 5 / x + 11 / x-3 - x-4 / x^2+2x-15