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.

3a + 4a = 7a

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 1 + 9 + 7 + 9
p = 26

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

b² + 14b + 14 = 4b + 5
b² + 14b + 14 - 5 = 4b
b² + 14b - 4b + 9 = 0
b² + 10b + 9 = 0

Next, factor the quadratic equation:

b² + 10b + 9 = 0
(b + 1)(b + 9) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (b + 1) or (b + 9) must equal zero:

If (b + 1) = 0, b must equal -1
If (b + 9) = 0, b must equal -9

So the solution is that b = -1 or -9

For parallel lines with a transversal, the following relationships apply:

• angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°)
• alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°)
• all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other
• same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°)

Applying these relationships starting with y° = 141, the value of c° is 39.

The formula for circumference is circle diameter x π:

c = πd
c = 15π