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
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.