6x + 6y = 7.50
10x + 5y = 8.75
( 6x + 6y = 7.50 ) 5
30x + 30y = 38.50
( 10x + 5y = 8.75 ) 3
30x + 15y = 26.25
If we subtract the last 2 equations,
15y = (38.50 - 26.25)
15y = 12.25
y = 0.817 dollars
30x = 14
x = 14/30
x = 0.47 dollars
so the cost of one apple is 0.47 dollars