Just number 3 is fine please but if you could also 4

3. r = -8

4. x = -5

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right

Equality Properties

Step-by-step explanation:

Step 1: Define equation

2(-5r + 2) = 84

Step 2: Solve for r

Divide 2 on both sides:                    -5r + 2 = 42Subtract 2 on both sides:                 -5r = 40Divide -5 on both sides:                    r = -8

Step 3: Check

Plug in r into the original equation to verify it's a solution.

Substitute in r:                   2(-5(-8) + 2) = 84Multiply:                             2(40 + 2) = 84Add:                                   2(42) = 84Multiply:                             84 = 84

Here we see that 84 does indeed equal 84.

∴ r = -8 is a solution of the equation.

Step 4: Define equation

264 = -8(-8 + 5x)

Step 5: Solve for x

Divide both sides by -8:                    -33 = -8 + 5xAdd 8 to both sides:                          -25 = 5xDivide 5 on both sides:                      -5 = xRewrite:                                               x = -5

Step 6: Check

Plug in x into the original equation to verify it's a solution.

Substitute in x:                    264 = -8(-8 + 5(-5))Multiply:                               264 = -8(-8 - 25)Subtract:                              264 = -8(-33)Multiply:                               264 = 264

Here we see that 264 does indeed equal 264.

∴ x = -5 is a solution of the equation.

Are you trying to figure out the volume?