On average a baby uses 3 times the number of large diapers as small diapers and double the number of medium diapers as small diapers. if the average baby uses 2940 diapers size large and small, how many of each size would be used

Okay, if I read this correctly, then the number of large diapers is three times as many as small, and the medium diapers are two times as many as small. To set this equation up, assign x as the unknown value. Small = x Medium = 2x and Large = 3x . Add all of these together and equal them to 2940. From here, solve the equation (6x=2940) by dividing the entire thing by 6. You will have x = 490.
To find the number of each size, plug it back into the original.
Large: 3x = 3(490) = 1470
Medium: 2x = 2(490) = 980
Small: x = 490
Hopefully I read the problem correctly.