A/b=c for b
please explain this is sorta confusing :'(

Use the multiplier method to incrases £258 by 43%

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?

Solve this system of equations. 12x − 18y = 27 4x − 6y = 10