Explain what it means when it says find the difference between 827 and 533

Jamie went to home depot. she bought 25 bags of soil that cost $9 per bag. she bought 15 pots at $8 each, and she bought 23 bags of pebbles at $15 each. she used a coupon that gave her $5 off for every 100 dollars she spent. how much did jamie pay at the end?

X+ y = 5 ; x - y =3 solve using linear combination

Equation for the calculation double 2 and then add 5