If we take one sandwich it would be 1: and if we add the fact that for every one sandwich 3 new sandwiches were made, we can make a 1:3 ratio. If for every 1 sandwich there are 3 more sandwiches then we would multiply the beginning amount of 20 sandwiches to both numbers in the ratio so it stays equivalent.
1 x 20 = 20 3 x 20 = 60
So we can say now that the ratio for 20 sandwich pieces there are 60 new sandwich pieces.
The new ratio being 20:60 thus the amount of sandwiches after they were cut in thirds is 60 sandwiches
326=12m+6c+x The reason your x does not have a number is because it is unknown so in order to solve for x you need to get rid of the 12m+6c so in order to that you can divide it on both sides so you would get 326/12m+6c=x the divide your numbers 18.1=x but you cant have a tenth of a djembe drum so you would have to round up to 19.