3 paper bags contain a total of 20 apples. The 1st and 2nd bag have a total of 9 apples. The 2nd and 3rd bag have a total of 17 apples. The 1st and third bag contain a total of how many apples.

3 answers

can someone please help me understand this?
suppose the bags contain x,y,z apples, respectively. Then you know that
x+y+z = 20
x+y = 9
y+z = 17
You want to find x+z
Combining the 2nd and 3rd equations,
x+2y+z = 26
Now using that with the 1st equation,
2(x+z)+2y = 40
(x+z) + 2y = 26
subtract to get
x+z = 14
Oh you're oobleck