Answer:
0.80A + 0.92B = 63 .....1
A + B = 75 ......2
Step-by-step explanation:
Let A and B represent the total possible score in part A and B respectively;
Analysing each sentence of the question;
Sam scored 80% on Part A of a math test and 92% on part B of the math test. His total mark on the test was 63
80% of A + 92% of B = 63
0.80A + 0.92B = 63 ......1
The total possible marks for the test was 75;
A + B = 75 .....2
So, equation 1 and 2 provides a set of simultaneous equations that can be used to represent and solve the situation.
Solving the simultaneous equations, we will arrive at;
Part A = 50
Part B = 25
You are right. In circle equation we have =r² so the correct answer will be C od D. But we have to calculate the center of a circle.

Complete the square:

And we have:

So the answer is C (the same left side of equation).
Answer:
do not know what the question is but the equation for this would be
y=2100-51x
Tell Me if I'm Wrong But I Believe It's 198m3