Question

Solv for x for all of these 1. 3x+6=21 2. 33=7x-9 3. 28=7+x need to know now please help !!!!!!

Answer 1

`\boxed{ \sf{ \bold{1. \: \: \: x = 5}}}`

`\boxed{ \sf{ \bold{2. \: \: x = 6}}}`

`\boxed{ \bold{ \sf{3. \: \: x = 21}}}`

Explanation:

1.
`\sf{3x + 6 = 21}`

Move constant to right hand side and change its sign

⇒
`\sf{3x = 21 - 6}`

Subtract 6 from 21

⇒
`\sf{3x = 15}`

Divide both sides of the equation by 3

⇒
`\sf{ (3x)/(3) = (15)/(3) }`

Calculate

⇒
`\sf{x = 5}`

--------------------------------------------------------

2.
`\sf{33 = 7x - 9 }`

Swap the sides of the equation

⇒
`\sf{7x - 9 = 33}`

Move constant to right hand side and change it's sign

⇒
`\sf{7x = 33 + 9}`

Add the numbers

⇒
`\sf{7x = 42}`

Divide both sides of the equation by 7

⇒
`\sf{ (7x)/(7) = (42)/(7) }`

Calculate

⇒
`\sf{x = 6}`

---------------------------------------------------------

3.
`\sf{28 = 7 + x}`

Swap the sides of the equation

⇒
`\sf{7 + x = 28}`

Move constant to right hand side and change it's sign

⇒
`\sf{x = 28 - 7}`

Subtract 7 from 28

⇒
`\sf{x = 21}`

Hope I helped!

Best regards!!