Question 94621
WHAT IS x?????
YOU SURE ARE ON THE RIGHT TRACK!!! I HAVE FOUND THAT LAYING OUT THESE WORD PROBLEMS AS I HAVE DONE BELOW MAKES THEM A LOT EASIER TO SOLVE BECAUSE YOU CAN ALWAYS SEE WHERE YOU ARE AND WHERE YOU ARE GOING. 


Let x=Ricardo's Sister's age
Then 2x-4=Ricardo's age (we are told this)

Now we are also told that the sum of their ages is 20.  So:

x+2x-4=20  add 4 to both sides

x+2x-4+4=20+4  collect like terms

3x=24  divide both sides by 3
x=8---------------------------------Ricardo's sister's age

2x-4=2*8-4=12 ------------------------Ricardo's age


CK

12+8=20
20=20

Also: 12 is 4 less than 2 times 8

Hope this helps---ptaylor