PLEASE HELP/ANSWER! From 1980 to 1990, Lior’s weight increased by 25%. If his weight was k kilograms in 1990, what was it in 1980?

Respuesta :

The weight in 1980 is [tex]\frac{4k}{5}[/tex] kilograms

Solution:

From 1980 to 1990, Lior’s weight increased by 25%

His weight is "k" kilograms in 1990

To find: weight in 1980

This is a percentage increase problem

Let "x" be the weight in kilograms in 1980

The percentage increase is given by formula:

[tex]\text{Percentage increase } = \frac{\text{Final value - initial value}}{\text{initial value}} \times 100[/tex]

Here,

Initial value in 1980 = x

Final value in 1990 = k

Percentage increase = 25 %

Substituting the values in formula,

[tex]25 = \frac{k-x}{x} \times 100\\\\25x = 100(k-x)\\\\x = 4(k-x)\\\\x = 4k - 4x\\\\5x = 4k\\\\x = \frac{4k}{5}[/tex]

Thus the weight in kilograms in 1980 is [tex]\frac{4k}{5}[/tex]

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