b must be equal to -6 for infinitely many solutions for system of equations
and 
<u>Solution:
</u>
Need to calculate value of b so that given system of equations have an infinite number of solutions

Let us bring the equations in same form for sake of simplicity in comparison

Now we have two equations

Let us first see what is requirement for system of equations have an infinite number of solutions
If
and
are two equation
then the given system of equation has no infinitely many solutions.
In our case,

As for infinitely many solutions 

Hence b must be equal to -6 for infinitely many solutions for system of equations
and
Answer:
The surface area is 3140 feet².
What is Surface Area?
Surface area is the amount of space covering the outside of a three-dimensional shape.
Given that:
Diameter = 20 feet
radius = 20 ÷ 2 = 10 feet
Now, Surface area will be,
=2πr²+ 2πrh
= 2 × 3.14 × (10)² + 2 × 3.14 × 10 × 40
= 6.28 × 100 + 6.28 × 400
= 628 + 25.12 × 100
= 628+ 2512
= 3140 feet²
hence, the surface area is 3140 feet².
Step-by-step explanation:
The answer is C A= 90 in^2. This is because the total area is represented by 10x18, which equals 180. The red occupies half of the flag, and 180 divided by 2 is 90.