Original number of buyers = x
Price of boat = xy
after 10 drop out price becomes (x-10)(y+1)
after 15 more drop out (x-25)(y+1+2) all three of these amounts are equal (the price of the boat)
xy-10y+x-10 = xy +3x - 25y -75=xy
x-10y -10 = 3x-25y-75=0
System of equations becomes: (solve for 'x' )
x-10y-10=0
3x-25y-75=0 multiply first equation by -2.5
-2.5x+25y+25=0 add them together
.5x-50 =0
x=100 original buyers 100-10y-10=0 90 = 10y y = 9 price of boat per person (TOTAL PRICE $900)