A school plans to spend twice the amount it did last year on its winter dance less the cost of the disco ball which was $150, since they have it from last year a total of $1,500 is being spent this year. fill the blanks to write an equation that will determine the amount of last years budget

Let's denote last year's budget as \( x \).

According to the problem, the school plans to spend twice the amount it did last year on the winter dance, minus the cost of the disco ball, which is $150. We can represent this mathematically with the following equation:

\[ 2x - 150 = 1500 \]

Now, we can rearrange the equation into the format you've provided, which is \( ? ( a - ? ) = ? \).

To express this idea:

We want to isolate \( 2x \) on one side:

\[ 2x - 150 = 1500 \]

Then, if we rearrange it, we can express it as:

\[ 2x = 1500 + 150 \]

This simplifies to:

\[ 2x = 1650 \]

Now we can divide both sides by 2 to find \( x \):

\[ x = 825 \]

If we want to fit it into your format, we can write:

Let \( a = 1650 \), and \( ? = 150 \).

Then the complete format will be:

\[ 2 ( x - 150 ) = 1500 \]

So filling the blanks as per your request:

1. ? = 2
2. a = x
3. ? = 150

So the equation can be interpreted as:

\[ 2 ( a - 150 ) = 1500 \]

Where \( a \) (last year's budget) equals \( 825 \).