Answer:
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Here are some formulas...
percent increase = (new number - original number) / original number...* 100
percent decrease = (original number - new number) / original number...* 100
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a student raises her grade from a 75 to a 90....since it is going from a smaller number to a larger number, u have an increase
percent increase = (90 - 75) / 70....* 100
= 15/70 * 100
= 0.2142 * 100
= 21.42 rounds to 21.4% increase
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36.50 on sale for 32.12...since it goes from a larger number to a smaller number, u have a decrease
percent decrease = (original number - new number) / original * 100
= (36.50 - 32.12) / 32.12...* 100
= 4.38 / 32.12...* 100
= 0.1363...* 100
= 13.63 rounds to 13.6% decrease
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23.5 to 21.2......this is a decrease
percent decrease = (original number - new number) / original...* 100
= (23.5 - 21.2) / 23.5....* 100
= 2.3 / 23.5....* 100
= 0.0979 * 100
= 9.79 rounds to 9.8% decrease
Answer:
Area = 370 m²
Cost to paint = £105
Step-by-step explanation:
Area of the wall of a cinema hall = Area of a trapezoid (1)+ Area of a rectangle (2) + Area of a trapezoid (3)
Area of a trapezoid = 
where 
and 
are the parallel sides and h is the distance between these sides.
Area of trapezoid (1) = 
= 69 m²
Area of the rectangle (2) = Length × Width
= 12 × 15
= 180 m²
Area of the trapezoid (3) = 
= 121 m²
Now area of the wall = 69 + 180 + 121
= 370 m²
One tin covers the area = 25 m²
Number of tins required to paint the wall = 
= 
= 14.8
Therefore, number of tins to be purchased = 15
Cost to paint the complete wall = 15 × £7
= £105
