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 equal sign and the answer on the other.

-3a - 8 = \( \frac{a}{9} \)
9 x (-3a - 8) = a
(9 x -3a) + (9 x -8) = a
-27a - 72 = a
-27a - 72 - a = 0
-27a - a = 72
-28a = 72
a = \( \frac{72}{-28} \)
a = -2\(\frac{4}{7}\)

The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 8 x 5 = \( \frac{40}{2} \) = 20

The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)² : a = π r².

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.

4a + 7a = 11a

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).