1.35 for 3 oranges is $0.45 per orange----------10x0.45=$4.5
1.8 for 4 oranges is $0.45 per orange------------10x0.45=$4.5
2.25 for 5 oranges is $0.45 per orange----------10x0.45=$4.5
or
$4.25 for 10 oranges is $0.425 per orange---------10x0.425=$4.25
It is cheaper to buy 10 oranges for $4.25 because the price per orange is $0.025 cheaper than all the other offers.