A deposit (in this case) is a portion of the TV paid in advance - 20% of the total cost. That means that the 96$ makes up the remaining 80% of the total cost, which I'll represent as x. From here, we can set up an equation to find the total cost x, since we have a relation to form it on - the fact that 80% of x is equal to 96$.
The total cost of the TV is 120 dollars.