The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(8²) + 2π(8 x 7)
sa = 2π(64) + 2π(56)
sa = (2 x 64)π + (2 x 56)π
sa = 128π + 112π
sa = 240π

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

8a - 2a = 6a

The coordinate grid is composed of a horizontal x-axis and a vertical y-axis. The center of the grid, where the x-axis and y-axis meet, is called the origin.

You need to find the value of b so solve the first equation in terms of y:

-6b + y = 8
y = 8 + 6b

then substitute the result (8 - -6b) into the second equation:

3b + 3(8 + 6b) = 4
3b + (3 x 8) + (3 x 6b) = 4
3b + 24 + 18b = 4
3b + 18b = 4 - 24
21b = -20
b = \( \frac{-20}{21} \)
b = -\(\frac{20}{21}\)

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the > sign and the answer on the other.

-6a - 1 > \( \frac{a}{-9} \)
-9 x (-6a - 1) > a
(-9 x -6a) + (-9 x -1) > a
54a + 9 > a
54a + 9 - a > 0
54a - a > -9
53a > -9
a > \( \frac{-9}{53} \)
a > -\(\frac{9}{53}\)