# Math Help - proportions i think

1. ## proportions i think

I don't understand the attached problem. Can someone help me get this started?

2. Hello, igottaquestion!

135) A sloping ramp is to be built with vertical supports at $B,C,D$ as shown.

The supports at $A$ and $E$ are 11 and 17 ft, respectively.

How high must the supports be at point $B,C,D$ ?

Code:
                                       o -
*  | :
o     | :
*  |     | :
*     |     | :
o        |     | :
*  |        |     | 6
*     |        |     | :
*        |        |     | :
o           |        |     | :
*  |           |        |     | :
o     |           |        |     | -
|     |           |        |     | :
|     |           |        |     | :
|     |           |        |     | :
11 |     |           |        |     | 11
|     |           |        |     | :
|     |           |        |     | :
|     |           |        |     | :
o - - o - - - - - o - - - -o- - -o -
A  12 B     30    C   18   D  12 E

x  =    12          42       60    72

Placing $A$ at the origin,
. . the equation of the ramp is: . $f(x) \:=\:\tfrac{1}{12}x + 11$

$\text{At }B\!:\;f(12) \:=\:\tfrac{1}{12}(12) + 11 \:=\:12$

$\text{At }C\!:\;f(42) \:=\:\tfrac{1}{12}(42) + 11 \:=\:\tfrac{29}{2}$

$\text{At }D\!:\;f(60) \:=\:\tfrac{1}{12}(60) + 11 \:=\:16$