Page 4 - 10-Math-3 VARIATIONS

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18x - 20x = 10 - 12 ⇒ - 2x = - 2 ⇒ x = 1

Thus the required numbers are
3x = 3(1) = 3
and 4x = 4(1) = 4.

Example 4: Find the ratio 3a + 4b : 5a + 7b if a : b = 5 : 8.

Solution: Given that

Version 1.1 (b) Proportion
A proportion is a statement, which is expressed as an equivalence
of two ratios. If two ratios a : b and c : d

are equal, then we can write a : b = c : d

where quantities a, d are called extremes, while b, c are called
means.
Symbolically the proportion of a, b, c and d is written as
a : b :: c : d
or a : b = c : d
or
i.e., ad = bc
This shows that, Product of extremes = Product of means.

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