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

7a + z = -8
z = -8 - 7a

then substitute the result (-8 - 7a) into the second equation:

9a - 7(-8 - 7a) = -2
9a + (-7 x -8) + (-7 x -7a) = -2
9a + 56 + 49a = -2
9a + 49a = -2 - 56
58a = -58
a = \( \frac{-58}{58} \)
a = -1

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.

-7b + 6 > 7 - 8b
-7b > 7 - 8b - 6
-7b + 8b > 7 - 6
b > 1

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

To solve this equation, isolate the variable for which you are solving (b) on one side of the equation and put everything else on the other side.

b - 5y = 7b + y - 7
b = 7b + y - 7 + 5y
b - 7b = y - 7 + 5y
-6b = 6y - 7
b = \( \frac{6y - 7}{-6} \)
b = \( \frac{6y}{-6} \) + \( \frac{-7}{-6} \)
b = -y + 1\(\frac{1}{6}\)

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.