A line on the coordinate grid can be defined by a slope-intercept equation: y = mx + b. For a given value of x, the value of y can be determined given the slope (m) and y-intercept (b) of the line. The slope of a line is change in y over change in x, \({\Delta y \over \Delta x}\), and the y-intercept is the y-coordinate where the line crosses the vertical y-axis.

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.

4a x 5b = (4 x 5) (a x b) = 20ab

A line segment is a portion of a line with a measurable length. The midpoint of a line segment is the point exactly halfway between the endpoints. The midpoint bisects (cuts in half) the line segment.

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 b so solve the first equation in terms of z:

2b + z = -8
z = -8 - 2b

then substitute the result (-8 - 2b) into the second equation:

-8b - 5(-8 - 2b) = -8
-8b + (-5 x -8) + (-5 x -2b) = -8
-8b + 40 + 10b = -8
-8b + 10b = -8 - 40
2b = -48
b = \( \frac{-48}{2} \)
b = -24