The cost price of the cycle is Rs.3240
Represent the cost price of the cycle with x and the selling price with y
A gain of 5% when the marked price is at a discount of 10% implies that:
[tex]5\%=\frac{(1 - 10\%)y-x}{x}[/tex]
Express 10% as decimal
[tex]5\%=\frac{(1 - 0.10)y-x}{x}[/tex]
[tex]5\%=\frac{0.90y-x}{x}[/tex]
Express 5% as decimal
[tex]0.05=\frac{0.90y-x}{x}[/tex]
Cross multiply
[tex]0.05x=0.90y-x[/tex]
Collect like terms
[tex]x + 0.05x=0.90y\\[/tex]
This gives
[tex]1.05x=0.90y[/tex]
Make y the subject of the formula
[tex]y = \frac{1.05x}{0.90}[/tex]
Also, when the discount is 5% and the profit is 351, we have:
[tex]351=(1 - 5\%)y -x[/tex]
Express 5% as decimal
[tex]351=(1 - 0.05)y -x[/tex]
This gives
[tex]351=0.95y -x[/tex]
Make y the subject
[tex]0.95y = 351 + x[/tex]
Substitute [tex]y = \frac{1.05x}{0.90}[/tex]
[tex]0.95 \times \frac{1.05x}{0.90} = 351 + x[/tex]
[tex]\frac{0.9975x}{0.90} = 351 + x[/tex]
Subtract x from both sides
[tex]\frac{0.9975x}{0.90} -x= 351[/tex]
Take LCM
[tex]\frac{0.9975x - 0.9x}{0.90}= 351[/tex]
[tex]\frac{0.0975x}{0.90}= 351[/tex]
Multiply both sides by 0.90
[tex]0.0975x= 315.9[/tex]
Divide both sides by 0.0975
[tex]x= 3240[/tex]
Hence, the cost price of the cycle is Rs.3240
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