Question 1208330
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x = cost price = amount Bob paid for the TV
y = marked price = amount that Bob's customer pays if no discounts are applied


0.15y = amount the customer saves if 15% discount is applied
y - 0.15y = 0.85y = amount the customer pays after the 15% discount
0.85y-x = profit Bob makes = 135
0.85y-x = 135
<font color=blue>x = 0.85y-135</font>
We'll use this later.


0.25y = amount the customer saves if 25% discount is applied
y - 0.25y = 0.75y = amount the customer pays after the 25% discount
0.75y-x = profit Bob makes = -65
0.75y-x = -65
0.75y-(<font color=blue>x</font>) = -65
0.75y-(<font color=blue>0.85y-135</font>) = -65 ....... plug in <font color=blue>x = 0.85y-135</font>
0.75y-0.85y+135 = -65
-0.10y+135 = -65
-0.10y = -65-135
-0.10y = -200
y = -200/(-0.10)
y = 2000
This is the amount the customer would pay if no discounts are applied.


Then,
x = 0.85y-135
x = 0.85*2000-135
x = <font color=red>1565 dollars</font> is the cost price of the TV.
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