I can't really help you with the math but I can give you the formulas for the answers.
Let O be the center of a circle. If <span>the measure of arc RS is 84 degrees, then m∠SOR=84^{0}. The triangle SOR is isoscales (because SO=OR as radii), so m∠RSO=m∠ORS=(180^{0}-84^{0}):2=48^{0}.
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Line RU is tangent to the circle in point R, this means that m∠ORU=90^{0}.
Consider the triangle SRU. m∠RSU=30^{0} and m∠SRU=48^{0}+90^{0}=138^{0}, then m∠RUS=180^{0}-30^{0}-138^{0}=12^{0}.
ANSWER: Correct choice B - 12^{0}.
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Well, let's say the numbers are "a" and "b"
so a * b = ab
ok... now, if we reduce "a" by 25%, that means the new size is just 75% of the old one, how much is 75% of a? well, (75/100) * a, or 0.75a
now let's reduce "b" by 50%, that means the new size is 50% or half, how much is 50% of b? well (50/100)*b, or 0.5b

now, the new size of "ab" is just 0.375ab... well, let's revert the decimal format by simply multiplying by 100
0.375 * 100, is 37.5%
the new size of "ab" is just 37.5% of the original "ab"
it decreased by 100 - 37.5 or 62.5%
N+2
n+4
n+6
n+2+n+4+n+6
3n+12=-6
3n=-18
n=-6
the value of the greatest integer is -2