Put your calculator in <em>degrees mode</em>.
1.45 is the correct number of <em>radians</em>.
To obtain a fast solution for this problem
I will graph both functions and find the points of intersection.
Looking at both graphs, we can see that the point of intersection is
(21.859,92.664)
The price for which the supply equals the demand is
21.859
1680 is the PERMUTATION answer.
Arlene; shadow 5ft: 6ft tall. = 5:6
billboard; shadow 35ft: x ft tall = 5:6.
35 * 6 / 5 = 42.
billboard is (C).42ft tall.