Word problem: 12 cherry-trees, remaining 5/7 of orchard are apple trees

[Mike236]

The answer key says the answer is 42 but I can't figure out how to get 42. I do know that some of the answers in the key are wrong.

"In an orchard there are 12 cherry-trees: the remaining 5/7 of the orchard are apple-trees: how many trees are there in the orchard?"

 

[dtrud]

The answer key says the answer is 42 but I can't figure out how to get 42. I do know that some of the answers in the key are wrong.

"In an orchard there are 12 cherry-trees: the remaining 5/7 of the orchard are apple-trees: how many trees are there in the orchard?"

Hello, If 5/7 of the orchards are apple trees then I'm going to assume the remaining 2/7 of the orchards are the cherry trees.
So, 2/7 of the total number of trees are cherry and there are 12 of them. If 2/7 of the total equals 12, then 1/7 of the total must equal 6 trees.
Now, we also know that 5/7 of the orchard is apple. If 1/7 = 6 trees, then 5/7 =30 trees, since 5*6=30.
If we check all of the math 5/7 of the trees are apple which =30 and 2/7 of the trees are cherry which =12, so there are a total of 42 trees.

Let me know if you still have questions, I will try to clarify.

Dave

 

[melis]

If you know that 5/7 of the trees are apple trees you know that 2/7 of the tree are cherry trees. Knowing this you can set up the proportion 2/7=12/x, and you can solve for x and you would get 42.

 

[Mike236]

Thanks guys!