5n + 2(12) = 39
5n + 24 = 39
5n = 39 - 24
5n = 15
n = 15/5
n = 3....Rebecca purchased 3 scarves
The ratio of the height to shadow length is a constant.
.. (5 ft)/(132 ft) = (tree height)/(144 ft)
.. (tree height) = (144 ft)*(5/132) = 5 5/11 ft
First simplify.
2-2n-5n+27= -7n+29.
then require this to be greater than 0 .
-7n+29>0
from here you can easily get that
n <29/7