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 + 9a = 17a

You need to find the value of c so solve the first equation in terms of y:

-9c + y = -2
y = -2 + 9c

then substitute the result (-2 - -9c) into the second equation:

c - 6(-2 + 9c) = -1
c + (-6 x -2) + (-6 x 9c) = -1
c + 12 - 54c = -1
c - 54c = -1 - 12
-53c = -13
c = \( \frac{-13}{-53} \)
c = \(\frac{13}{53}\)

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 factor a quadratic expression, apply the FOIL (First, Outside, Inside, Last) method in reverse.

A cylinder is a solid figure with straight parallel sides and a circular or oval cross section with a radius (r) and a height (h). The volume of a cylinder is π r²h and the surface area is 2(π r²) + 2π rh.