Alright, lets get started.
Suppose total number of dancers in school = x
We have given in question, 42 % of total dancers are ballet dancers.
So, we could find number of ballet dancers by finding 42 % of total dancers.
Number of ballet dancers = x * 42 %
Number of ballet dancers = x * 42/100 = 0.42 x
As per given in question, there are 63 ballet dancers in school.
Which means 0.42 x = 63
Dividing 0.42 from both sides
0.42 x / 0.42 = 63 / 0.42
x = 150
Hence number of total dancers in school = 150 : Answer
Hope it will help :)
If you have multiple equations with multiple variables, you can either do clever substitutions, or turn it into a matrix on which you can perform linear combinations or multiplications (Gauss elimination)
1 1 1 1
2 1 -1 8
1 -1 1 -5
(note how the above 3 rows represent the 3 equations, just got rid of the variables, plus sign and equals sign)
subtract row1 from row3, that eliminates x and z from row 3.
1 1 1 1
2 1 -1 8
0 -2 0 -6
divide row3 by -2, that will give y a factor of 1
1 1 1 1
2 1 -1 8
0 1 0 3
The last row now says y=3
Answers:
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1) (3 inches)(5 inches) = (3 in)(5 in) = 3 * 5 * in * in = 15 * in * in = " 15 in² " .
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2) (5 feet)(2 feet) = (5 ft)(2ft) = 5 * 2 * ft * ft = 10 * ft * ft = " 10 ft² " .
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