Think of this as a ratio. 5 tsp : 6 batches
Set it up the same with the question.
? tsp: 12 batches
Ok now let’s think about equivalent ratios for this.
5 tsp : 6 batches
What did we do to the 6 batches to get to 12 batches? We doubled it. 6x2. So we should do the same to 5. Double 5 as well. 5x2 is 10. So.....
10 tsp : 12 batches
Also if you think about it 10:12 is equivalent to 5:6.
Hope this helped! :)
