Answer:
15
Step-by-step explanation:
x - y = 10, then x = 10 + y
x + y = 20
substitute for x:
10 + y + y = 20
2y = 10
y = 5
x = 10 + 5 = 15
Answer:
option (2) is correct.

Step-by-step explanation:
Given two similar rectangles and with dimension of sides,
we have to choose the correct proportion for corresponding sides.
Since, the rectangles given are similar rectangles.
So, the corresponding sides are in same proportion in case of similar figures,
So,

Thus, option (2) is correct.
Answer:
Step-by-step explanation:
Given that there is a function of x,

Let us find first and second derivative for f(x)

When f'(x) =0 we have tanx = 1 and hence
a) f'(x) >0 for I and III quadrant
Hence increasing in 
and decreasing in 


Hence f has a maxima at x = pi/4 and minima at x = 3pi/4
b) Maximum value = 
Minimum value = 
c)
f"(x) =0 gives tanx =-1

are points of inflection.
concave up in (3pi/4,7pi/4)
and concave down in (0,3pi/4)U(7pi/4,2pi)