The width of a photograph is 4 centimeters more than three tenths of the length. If the width is 13 cm, what is the length?

1 Answer
CountryGirl
May 9, 2018

#30# cm long

Explanation:

I will give the #"width"# the variable #w#, and the #"length"# the variable #l#.

There are two equations to be made from the given information. Here are a couple things to remember before I make the equations:

  1. The word "is" means "equals", so everywhere you see the word "is", you can use an #=# sign.
  2. "More than" means addition, and "less than" means subtraction. So you can use a #+# sign and a #-# sign if you see those phrases.
  3. "Three tenths" is the written out form of #3/10#, so I will be using that in the equation.

So here are the phrases turned into equations:

#stackrel(w)overbrace"The width of a photograph"stackrel(=)overbrace"is"stackrel(3/10l + 4)overbrace"4 centimeters more than three tenths of the length"#

#w = 3/10l + 4#

#stackrel(w)overbrace"The width"stackrel(=)overbrace"is"stackrel(13)overbrace"13 cm"#

#w = 13#

Now put the value for #w# into the equation to solve for #l#:

#w = 3/10l + 4#

#(color(blue)13) = 3/10l + 4#

#13 -color(green)(4) = 3/10l + cancel4 -color(green)cancel4#

#color(blue)9 = 3/10l#

#9(color(green)10) = 3/cancel10cancelcolor(green)10l#

#color(blue)(90) = 3l#

#90/3 = l#

#30 = l#

The photo is #30# cm long.

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