15 x 25 = 375
15 x 50 = 750
375 + 750 = 1,125
She has 1,125 books.
Step 1
Find the area of one equilateral triangle
Applying the law of sines

in this problem
a=b=7 cm
C=60 degrees
so

cm²
Step 2
To calculate the area of the hexagon multiply the area of one equilateral triangle by 
cm²
therefore
the answer is the option
73.5 sqrt 3cm²
Answer:
14,000+2.1%(0.021)x
Step-by-step explanation:
x is how many years