Answer:
Class 7A collected 4.8 ounces of pure gold.
Step-by-step explanation:
<u>Key skills required are: Percentages, Multiplication</u>
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- We only need the information about Class 7A. They collected 40 oz that contains 12% gold.
- In other words, this means that 12% of that 40 oz gold sand is pure gold.
Here we have to do 12% x 40 to find the number of oz of pure gold. We first have to convert 12% into a decimal. Divide it by a 100 (or move the decimal point 2 places to the left) and you will get 0.12.
<em>Do 0.12 x 40 and you will get 4.8</em>
Therefore, there are 4.8 oz of pure gold in Class 7A's gold sand
To solve this problem, let us first assign some
variables. Let us say that:
x = pigs
y = chickens
z = ducks
From the problem statement, we can formulate the
following equations:
1. y + z = 30 --->
only chicken and ducks have feathers
2. 4 x + 2 y + 2 z = 120 --->
pig has 4 feet, while chicken and duck has 2 each
3. 2 x + 2 y + 2 z = 90 --->
each animal has 2 eyes only
Rewriting equation 1 in terms of y:
y = 30 – z
Plugging this in equation 2:
4 x + 2 (30 – z) + 2 z = 120
4 x + 60 – 2z + 2z = 120
4 x = 120 – 60
4 x = 60
x = 15
From the given choices, only one choice has 15 pigs. Therefore
the answers are:
She has 15 pigs, 12 chickens, and 18 ducks.
- 9 + 7
-2
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Answer:
19y-9
Step-by-step explanation:
apply distributive property
-3(-4y)-3 x 3 + 7y
12y - 3 x 3 + 7y
12y - 9 + 7y
add 12y to 7y
19y-9
Answer:
x = 20
Step-by-step explanation:
Write and solve an equation of ratios, as follows:
1 3/4 14
------------ = --------
2 1/2 x
where x is the unknown number.
Converting the mixed numbers to improper fractions, we get:
7/4 14
------ = -----
5/2 x
Here there are two numerators and two denominators. Multiplying all four quantities by 4 will remove some of the fractions:
7 56
------ = -------
10 4x
Cross multiplying, we get:
28 x = 560, or x = 20
