To deliver mulch, lawn and gardens charge $30 per cubic yard of mulch plus a $30 delivery fee. yard depot charges $25 per cubic yard of mulch plus an extra $55 delivery fee. for how many cubic yards will the cost be the same? what will the cost be?

So lawn and gardens will be 55 for one square yard and yard depot will be 80.
lawn and gardens costs 5 more for each cubic yard
80- 55 to get the difference in costs
25 is the difference 
25/5 
5 extra yards will be needed 
proof:
lawn and garden = l
yard depot = y
l=30x +30
y=25x+55
30(5) +30
150+30
180

25(5) + 55 
125 + 55
180

let's solve :

Plugging the values of a and b