The answer is c i hope this help you out.
Answer:
9 years old.
Step-by-step explanation:
Since the ages of all of these students are being represented in relation to the middle student's age then we can create formulas for each student and then apply them to the formula for the sum of their ages and solve for the middle child's age (M) like so... (oldest child's age is represented by variable O and youngest child's age is represented by variable Y)
O = M + 6
Y = M - 3
30 = (M+6) + M + (M-3) ... combine like terms
30 = 3M + 3 ... subtract 3 from both sides
27 = 3M ... divide both sides by 3
9 = M
Now we know that the middle child is 9 years old.
Answer: 
Step-by-step explanation:
To solve for y, we want to make sure y is isolated. SInce y is already isolated, all we need to do is divide both sides of the equation by 3.
[divide both sides by 3]
or
To answer this you will use the formula V = pi x radius ^2 x height. The substitution for this would be 3.14 x 4^2 x 8. The approximate answer is 401.92 cubic units. 3.14 is an approximation of pi.
Note: It does not say that x is the height, but this is the only piece of information missing without an obvious label, so I am using it as the height.
