What is 5x=y-4 in standard form ?

Use the elimination method to solve the system of equations -x+5y=-4 and 4x+3y=16

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 jame pay at the end?

Solve the formula ax+ by = c for x.