In a large backyard there 4 times as many shrubs as trees. Altogether, there are 40 trees and shrubs. How many trees are in the yard? How many shrubs?

Question

 

 Im a mom and don't know how to explain or solve this...darn. 

Answer 1

The trick to these sorts of problems is to find and set up the two linear equations and find the point where they meet, kind of like triangulation.

 

Here's what we know:

s + t = 40 (there are a total of 40 shrubs and trees)

s = 4t (the number of shrubs is equal to 4 times the number of trees)

 

Since our second equation gives us a value for a variable, we can plug that in to the first one:

4t + t = 40

simplify:

5t = 40

 

Divide both sides by 5:

5t / 5 = 40 / 5

t = 8

 

Now that we have t, we can find s:

s = 4 * 8

s = 32

 

Now to check:

32 + 8 = 40

40 = 40