To find the remaining part of the budget, we need to subtract the parts used for the DJ and the chaperones from the total budget.
The part used for the DJ is 3/5, and the part used for the chaperones is 1/4.
We can first find the common denominator of 5 and 4, which is 20.
Now we can convert the fractions to have a denominator of 20.
The part used for the DJ is equivalent to (3/5) * (4/4) = 12/20 of the budget.
The part used for the chaperones is equivalent to (1/4) * (5/5) = 5/20 of the budget.
Next, we subtract the parts used for the DJ and the chaperones from the total budget:
Total budget - Part used for DJ - Part used for chaperones = Remaining part of the budget
1 - 12/20 - 5/20 = (20/20) - (12/20) - (5/20)
= (20 - 12 - 5)/20
= 3/20 of the budget
Therefore, the remaining part of the budget to pay for decorations and snacks is 3/20 of the budget.