The answers below are given in the form ax + by + c = 0. They may differ slightly from your answers.
It is conventional in this form to have a positive and no fractions. This is achieved by multiplying through the equation by the appropriate number.

1. a. 3x + 2y − 4 = 0
  b. 4x − y − 8 = 0
  c. 2x − y − 4 = 0
  d. 3x − 5y − 9 = 0
  e. 2x + 6y − 3 = 0
  f. 2x + 8y − 3 = 0
  g. 12x + 9y − 3 = 0
2. a. y = 6x − 4 Gradient = 6
  b. y = -2x + 1.5 Gradient = -2
  c. y = 5x − 12 Gradient = 5
  d. y = -3x + 6 Gradient = -3
  e. y = -4x / 5 + 4 Gradient = -4/5
  f. y = 4x / 7 − 4/7 Gradient = 4/7
  g. y = 3x / 2 − 9 Gradient = 3/2

3. a. Angle is 33.7°
b. Angle is 153.4°
c. Angle is 14°

4. a. 3x − y + 4 = 0
b. 3x − 2y − 4 = 0
c. x + 2y − 1 = 0

5. a. y = 0.5x + 1.5

b. y = -2x + 1

6. a. 2x − y = 0
  b. 3x + y − 9 = 0
  c. x − 2y − 3 = 0
  d. x − y = 0
  e. 3x − 4y + 33 = 0
  f. 5x + 2y − 15 = 0
  g. y − 2 = 0
7. a. 5x − 3y − 3 = 0
  b. 8x + 3y − 7 = 0
  c. 14x − 3y − 40 = 0
  d. 7x + y + 22 = 0
  e. 9x + 22y − 166 = 0
  f. 4x − 3y + 12 = 0
  g. x − y = 0