To determine the amount of last year's budget for the winter dance, we can set up an equation based on the information provided.
Let \( x \) represent last year's budget. According to the problem:
- The school plans to spend twice the amount it did last year on the winter dance, so this would be \( 2x \).
- The disco ball cost $150, and since they already have it, we can subtract this cost from the total budget for this year's dance.
The total amount being spent this year is $1500, so we can set up the equation as follows:
\[ 2x - 150 = 1500 \]
Now you can solve for \( x \) to find last year's budget.
Solve for \( x \):
- Add 150 to both sides:
\[ 2x = 1500 + 150 \]
\[ 2x = 1650 \]
- Divide both sides by 2:
\[ x = \frac{1650}{2} \]
\[ x = 825 \]
Thus, last year's budget was $825.