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.

2a + 9a = 11a

A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

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

9a + x = -6
x = -6 - 9a

then substitute the result (-6 - 9a) into the second equation:

-a - 7(-6 - 9a) = 7
-a + (-7 x -6) + (-7 x -9a) = 7
-a + 42 + 63a = 7
-a + 63a = 7 - 42
62a = -35
a = \( \frac{-35}{62} \)
a = -\(\frac{35}{62}\)

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

a = ½bh
a = ½ x 6 x 6 = \( \frac{36}{2} \) = 18

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.

8a⁹ + 7a⁹ = 15a⁹