Answer:
3
Step-by-step explanation:
27 km
9 km every hour
so 27/9=3

For each subset it can either contain or not contain an element. For each element, there are 2 possibilities. Multiplying these together we get 27 or 128 subsets. For generalisation the total number of subsets of a set containing n elements is 2 to the power n.
x = 37.5 (or) 
Solution:
Given 
AC = 50, DE = 30, EC = 25, BE = x, BC = 25 + x
To find the value of x:
Property of similar triangles:
If two triangles are similar then the corresponding angles are congruent and the corresponding sides are in proportion.


Do cross multiplication, we get


Subtract 30x from both sides of the equation.

Divide by 20 on both sides of the equation, we get
x = 37.5 (or) 
Hence the value of x is 37.5 or
.
A(x - x₁)(x - x₂) = 0
a=5, x₁=-3, x₂ = 3
so:
5(x-(-3))(x-3)=0
5(x+3)(x-3)=0
5(x²-9) = 0
5x² - 45 = 0 ← answer