# solving basic equations

• Jan 23rd 2009, 11:41 AM
Leona_Marie
solving basic equations
The cost of a meal, including a 20% tip, is \$21.60. How much was the meal without the tip?
The tip is 20% of x or 0.2x
Together, x + 0.2x =\$21.60
1.2x =21.6
x = 18
what does x = in 0.2x and how would you find it
• Jan 23rd 2009, 11:43 AM
TheMasterMind
Quote:

Originally Posted by Leona_Marie
The cost of a meal, including a 20% tip, is \$21.60. How much was the meal without the tip?
The tip is 20% of x or 0.2x
Together, x + 0.2x =\$21.60
1.2x =21.6
x = 18
what does x = in 0.2x and how would you find it

0.2 x is the percentage (20%) as a decimal
• Jan 23rd 2009, 05:51 PM
mollymcf2009
Originally Posted by Leona_Marie http://www.mathhelpforum.com/math-he...s/viewpost.gif
The cost of a meal, including a 20% tip, is \$21.60. How much was the meal without the tip?
The tip is 20% of x or 0.2x
Together, x + 0.2x =\$21.60
1.2x =21.6
x = 18
what does x = in 0.2x and how would you find it

When you want to find out what the percentage of something is, you multiply it by that percentage. If you have 20% of \$1 you have 20 cents.

Think about it this way: If you have \$1.00, you have 100% of it. If you give me 20 cents you will have \$0.80 cents left over. Look at what 80 cents look like --> 0.80 which is the same as 80%
So you gave me 20% of your dollar and you have 80% left.

x is your unknown value. What is the unknown value that the question asks for or what are you trying to find by solving this equation? The original cost of the meal, right? So that is what x would be!
x + .2x = 21.6 --> x = original cost of meal, .2x = cost of meal x 20% of that cost
• Jan 24th 2009, 10:32 AM
Leona_Marie
Quote:

Originally Posted by mollymcf2009
Originally Posted by Leona_Marie http://www.mathhelpforum.com/math-he...s/viewpost.gif
The cost of a meal, including a 20% tip, is \$21.60. How much was the meal without the tip?
The tip is 20% of x or 0.2x
Together, x + 0.2x =\$21.60
1.2x =21.6
x = 18
what does x = in 0.2x and how would you find it

When you want to find out what the percentage of something is, you multiply it by that percentage. If you have 20% of \$1 you have 20 cents.

Think about it this way: If you have \$1.00, you have 100% of it. If you give me 20 cents you will have \$0.80 cents left over. Look at what 80 cents look like --> 0.80 which is the same as 80%
So you gave me 20% of your dollar and you have 80% left.

x is your unknown value. What is the unknown value that the question asks for or what are you trying to find by solving this equation? The original cost of the meal, right? So that is what x would be!
x + .2x = 21.6 --> x = original cost of meal, .2x = cost of meal x 20% of that cost

molly, thank you that was the answer I was looking for(Clapping)