Answer: (a) y = -3x + 10
                 
  
<u>Step-by-step explanation:</u>
The slope of line CD is perpendicular to line OB, which means they have opposite and reciprocal slopes. 
Step 1: Find the slope of OB using the formula: 
(x₁, y₁) = (0, 0) and (x₂, y₂) = (3, 1)

Step 2: Find the slope of CD (opposite and reciprocal of OB)

Step 3: Input the perpendicular slope and the slope into the Point-Slope formula: y - y₁ = m(x - x₁) 
(x₁, y₁) = (3, 1) because it is the point the line will pass through
y - 1 = -3(x - 3) 
y - 1 = -3x + 9      <em>distributed -3 into (x - 3)</em>
y      = -3x + 10    <em>added 1 to both sides</em>
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The x-intercept of DQ is the same x-intercept as CD.  The x-intercept is when y = 0
y = -3x + 10 
0 = -3x + 10
-10 = -3x       subtracted 10 from both sides
 <em>divided both sides by -3</em>
    <em>divided both sides by -3</em>