Question

-2(2r + 10) = 4(9r - 5) please help and show work i don't understand:/

Answer 1

When you are solving for a single variable (r) your main goal is to get it on one side of the equation.

(1) decide which side you want to get r on
(2) I like to circle the variables
(3) look right around the circle and apply the opposite operation to get the term on the other side of the equation

Where opposite operations + / - , Division / Multiplication

Answer 2

Ok so first distribute and multiply:\[-4r -20 =36r -20\]
Then subtract 36r from both sides:\[-40r-20=-20\]
Add 20 to both sides:
\[-40r = 0\]
divide by -40:
\[r=0\]

Answer 3

thanks !

Answer 4

Simplifying
-2(2r + 10) = 4(9r + -5)

Reorder the terms:
-2(10 + 2r) = 4(9r + -5)
(10 * -2 + 2r * -2) = 4(9r + -5)
(-20 + -4r) = 4(9r + -5)

Reorder the terms:
-20 + -4r = 4(-5 + 9r)
-20 + -4r = (-5 * 4 + 9r * 4)
-20 + -4r = (-20 + 36r)

Add '20' to each side of the equation.
-20 + 20 + -4r = -20 + 20 + 36r

Combine like terms: -20 + 20 = 0
0 + -4r = -20 + 20 + 36r
-4r = -20 + 20 + 36r

Combine like terms: -20 + 20 = 0
-4r = 0 + 36r
-4r = 36r

Solving
-4r = 36r

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '-36r' to each side of the equation.
-4r + -36r = 36r + -36r

Combine like terms: -4r + -36r = -40r
-40r = 36r + -36r

Combine like terms: 36r + -36r = 0
-40r = 0

Divide each side by '-40'.
r = 0.0

Simplifying
r = 0.0

Answer 5

Hope this is all right :D