I need help with quiz

Plz which expression is equivalent to the expression below?

Look at arnold's attempt to solve the equation for b: 3b = 12 b = 3 · 12 b = 36 describe the mistake that arnold made.

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?