Question 1001991
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y = {{{k/x}}},     (1)

according to the condition. &nbsp;Substitute here &nbsp;y = 4 &nbsp;and &nbsp;x = {{{1/2}}}. &nbsp;It will gives you the value for &nbsp;k.

After finding &nbsp;k, &nbsp;substitute &nbsp;y = 10 into &nbsp;(1) &nbsp;and determine &nbsp;x.

It is so easy . . . 
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