SOLUTION: 80% of a number is equivalent to the sum of the number and 5. What is the number? Write an equation in one variable and solve. Here is what I am starting with. x(.80)=x+5 Di

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: 80% of a number is equivalent to the sum of the number and 5. What is the number? Write an equation in one variable and solve. Here is what I am starting with. x(.80)=x+5 Di      Log On


   

Question 127394: 80% of a number is equivalent to the sum of the number and 5. What is the number? Write an equation in one variable and solve.
Here is what I am starting with.
x(.80)=x+5
Did I write the equation right? How do you figure out which side of the equation to leave x on?
I feel so lost. Thank you.
Found 2 solutions by jim_thompson5910, Earlsdon:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
You're off to a great start. Now you need to solve for x. It does not matter which side to leave x on (just make sure that all of the x terms are on the same side), but I usually like to get all of the x terms to the left side.


x%28.80%29=x%2B5+ Start with the given equation


0.80x=x%2B5+ Rearrange the terms


0.80x-x=5+ Subtract x from both sides


-0.20x=5+ Combine like terms


x=5%2F%28-0.20%29+ Divide both sides by -0.20 to isolate x


x=-25+ Divide


So the number is -25


Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
You've started out just fine.
(0.80)x = x+5 Now you need to isolate the x, and it really doesn't matter which side of the equation it ends up on. Start by subtracting 5 from both sides.
0.8x-5 = x Now subtract 0.8x from both sides.
(0.8x-0.8x)-5 = (x-0.8x)
-5 = 0.2x Finally, divide both sides by 0.2
-5/0.2 = x, so...
x = -25
Check:
(0.80)x = x+5 Substitute x = -25
(0.8)(-25) = -25+5 Simplify.
-20 = -20 The solution works!