book Maths Puzzle Numerical Ability

Without graphing, identify the following pair of lines as either "parallel", "perpendicular", or neither.

y = 4x + 4
y = -4x +3

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book Other Question

If the length of thread on a bolt is equal to twice the diameter plus 1/4",
how much thread would a 1/2" (diameter) bolt have?
I need help with Lines.
Question is: Find the slope and y-intercept of each line. y = 2x + 3 I have the answer in the book, However I want to know how they came up with it? Answer:Slope = 2
y-intercept = 3

Thank you