Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).

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

9b + x = 8
x = 8 - 9b

then substitute the result (8 - 9b) into the second equation:

-8b + 8(8 - 9b) = -6
-8b + (8 x 8) + (8 x -9b) = -6
-8b + 64 - 72b = -6
-8b - 72b = -6 - 64
-80b = -70
b = \( \frac{-70}{-80} \)
b = \(\frac{7}{8}\)

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(2a)(3ab) + (5a²)(5b)
(2 x 3)(a x a x b) + (5 x 5)(a² x b)
(6)(a¹⁺¹ x b) + (25)(a²b)
6a²b + 25a²b
31a²b

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 + 4a = 12a

The formula for circumference is circle diameter x π. Circle diameter is 2 x radius:

c = πd
c = π(2 * r)
c = π(2 * 6)
c = 12π