book Maths Puzzle Numerical Ability

I NEED HELP FACTORING:
X^2 - 6X + 5

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book Other Question

choose the correct x + yi form for : 2(cos 120 degrees + i sin 120 degrees) A store advertises an air conditioner on sale for $280. If this is marked down 20%, what was the original price.

Again I tried to use a proportion or multiply 20% x 280 and I do not get the answer in my book. Please help me.