When they say to solve for a variable, they want you to isolate/get the variable by itself.
5.) Solve for b (get b by itself)
Multiply 2 on both sides to get rid of the 1/2
2A = bh Divide h on both sides
6.) Solve for r
Divide 2 and 
on both sides
Answer:
-The equation r+b-33 represents the total number of marbles
-There 9 black marbles
-There are 24 red marbles
Step-by-step explanation:
The bag contains 33 red and black marbles. Let the number of black marbles be b and that of red marble to r
Total number of marbles will be
b+r = 33 i.e b+r-33 = 0... (1)
If the number of red marbles is 6 more than double the number of black marbles, this can be represented as;
r = 6+ 2b... (2)
Substituting 2 in eqn 1 we have;
b + 6+2b = 33
3b = 27
b = 9
r = 33-9
r = 24
This shows that there are 9 black marbles, 24 red marbles and the equation r+b-33 represents the total number of marbles in the bag.
Answer: 784π mm²
Step-by-step explanation: To find the area of a circle, start with the formula for the area of a circle which is shown below.
Area = πr²
Notice that here, we're given the diameter instead of the radius.
Remember that the radius is equal to half of the diameter. So the radius of this circle will be equal to half 56 millimeters or 28 millimeters.
So plugging into the formula, we have (π)(28 mm)².
A common mistake is to plug 56 millimeters into the formula but remember that we must plug in the radius and not the diameter.
Multiplying, (28 mm)² is equal to (28 mm)(28 mm) or 784 mm².
So we have 784π mm².
So the area of the circle is 784π mm².
