4th grade math problem

Question

Javier rode his bike for a total of 41 minutes. Before lunch, he rode for 1 minute less than 5 times the number of minutes he rode after lunch. How many minutes did Javier ride before lunch?

Answer 1

Let's  say A is the time he rode his bike after lunch, and Let's say B is the time he rode his bike after lunch.

 

We know the time he rode his bike was 41 minutes in total. Therefore,

 

A + B =41 .....................................(equation #1)

 

Then, we know that before lunch he rode his bike 1 minutes less than 5 times the time after lunch. Therefore:

 

B = (5A) - 1  (5 times the time after lunch minus 1 minute) ...................( equation #2)

 

If we replace B from the equation #2 into equation #1 we have:

 

A + (5A) -1 = 41

 

6A = 42

 

A = 7 

 

That means the time he rode his bike after lunch was 7 minutes. But the question is how many minutes he rode before lunch. Therefore, we have to replace this value in one of the equations (It doesn't matter which one).

 

So, I chose equation #2

 

B = 5A - 1  =>  B= (5 x 7) - 1

 

B = 35 - 1

 

B = 34

 

Then, the answer is: Javier rode his bike 34 minutes before lunch.