book Maths Puzzle Numerical Ability

I need help doing this problem:
(4x + 3w^2)(4x - 3w^2)

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book Other Question

a car travel 28 miles in 30 mins how many miles per hour was the car traveling I hav this homework, It says: 2/8g=(-14) How would I go about solving this problem and others like it?

(3 2/3)x=-5 1/2
(-3/8)x=12
(1 1/3)x= -4.82

Thanks