Let $x = the cost of 2nd chess set.
The 1st chess set costs $5
The 2nd chess set costs $x
The 3rd chess set costs $(5+x) <-- add the previous two, $5+$x
The 4th chess set costs $(5+2x) "
The 5th chess set costs $(10+3x) "
The 6th chess set costs $(15+5x) "
The 7th chess set costs $(25+8x) "
The 8th chess set costs $(40+13x) "
And since the 8th chess set is the
most expensive and is given to be
$196, we have the equation
$(40+13x) = $196
40+13x = 196
13x = 156
x = 12
So their prices are
$5, $12, $17, $29, $46, $75, $121, $196
Edwin