[list][*]Noah says that [math]9x-2x+4x[/math] is equivalent to [math]3x[/math], because the subtraction sign tells us to subtract everything that comes after [math]9x[/math].[/*][*]Elena says that [math]9x-2x+4x[/math] is equivalent to [math]11x[/math], because the subtraction only applies to [math]2x[/math].[/*][/list]Do you agree with either of them? Explain your reasoning.

Identify the error in generating an expression equivalent to [math]4+2x--\frac{1}{2}\left(10-4x\right)[/math]. Then correct the error.[br][br][math]4+2x+\frac{-1}{2}\left(10+\left(-4x\right)\right)[/math][br][math]4+2x+(-5)+2x[/math][br][math]4+2x-5+2x[/math][br][math]-1[/math]

Select [b]all [/b]expressions that are equivalent to [math]5x-15-20x+10[/math].

Write an inequality to represent this situation.

Solve the inequality you wrote and describe what the solution means in the situation.

For every $9 that Elena earns, she gives  dollars to charity. This happens 7 times this month. Elena wants to be sure she keeps at least $42 from this month’s earnings. [br][math]7\left(9-x\right)\ge42[/math]

Lin buys a candle that is 9 inches tall and burns down [math]x[/math] inches per minute. She wants to let the candle burn for 7 minutes until it is less than 6 inches tall. [br][math]9-7x<6[/math]

A certain shade of blue paint is made by mixing [math]1\frac{1}{2}[/math] quarts of blue paint with 5 quarts of white paint. If you need a total of 16.25 gallons of this shade of blue paint, how much of each color should you mix?