# Need some math help **URL:** \ **Category:** Factual Questions\ **Created:** [June 20, 2006, 1:09am UTC](https://boards.straightdope.com/t/need-some-math-help/361371 "2006-06-20T01:09:04Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [June 20, 2006, 1:09am UTC](https://boards.straightdope.com/t/need-some-math-help/361371/1 "2006-06-20T01:09:04Z")
Ok, this is homework related but not my homework. My nephew is asking for help and while I think I should know this it has been so long much past basic arithmetic eludes me. Wanting to be a cool uncle I am looking for help here. Any explanation you might give would be great. I can see what x should be but I am looking for the way to properly show the process here. Solve for x: 5(7-2x)=20 ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [June 20, 2006, 1:11am UTC](https://boards.straightdope.com/t/need-some-math-help/361371/2 "2006-06-20T01:11:36Z")
5(7-2x)=20 35 -20x = 20 [subtract 35 froim both sides] -20x= -15 [divide both sides by -20] x =15/20 = .75 ---
**Author:** ![tremorviolet](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@tremorviolet](https://boards.straightdope.com/u/tremorviolet)\ **Post date:** [June 20, 2006, 1:15am UTC](https://boards.straightdope.com/t/need-some-math-help/361371/3 "2006-06-20T01:15:37Z")
5(7-2x)=20 Step by step: Distribute the 5 to get: 5_7 - 5_2x = 20 35 - 10x = 20 Subtract 35 from both sides: 35 - 10x - 35 = 20 - 35 -10x = -15 Multiply by -1: (-1)(-10x) = (-1)(-15) 10x = 15 Divide by 10: 10x/10 = 15/10 x = 3/2 or 1 1/2 ---
**Author:** ![Campion](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@Campion](https://boards.straightdope.com/u/Campion)\ **Post date:** [June 20, 2006, 1:18am UTC](https://boards.straightdope.com/t/need-some-math-help/361371/4 "2006-06-20T01:18:25Z")
I’d actually divide both sides by 5 first, giving you: 7-2x=4 Subtract 7 from both sides: -2x=-3 Solve for x by dividing both sides by -2: x= 1.5 ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [June 20, 2006, 1:21am UTC](https://boards.straightdope.com/t/need-some-math-help/361371/5 "2006-06-20T01:21:23Z")
> [@John Mace](#): > > 5(7-2x)=20 > > 35 -20x = 20 [subtract 35 froim both sides] > -20x= -15 [divide both sides by -20] > x =15/20 = .75 5x2 = 20? My bad. The others got it right. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [June 20, 2006, 1:26am UTC](https://boards.straightdope.com/t/need-some-math-help/361371/6 "2006-06-20T01:26:02Z")
Thanks all. I over complicated the problem in my head trying to do too many steps at once (don’t ask…dunno why myself).