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