To find the cost for a garden that has a length of 4 yards and a width of 3 yards, we can substitute the values of l = 4 and w = 3 into the formula:
1.50(2l+2w)
= 1.50(2(4)+2(3))
= 1.50(8+6)
= 1.50(14)
= $21.00
Therefore, the cost for a garden that has a length of 4 yards and a width of 3 yards is $21.00.