I'm learning Ruby and I hope you can help me. This is my first question :)

I'm doing and exercise where I have the following hash:

```
sales = {
January: 15000,
February: 22000,
March: 12000,
April: 17000,
May: 81000,
June: 13000,
July: 21000,
August: 41200,
September: 25000,
October: 21500,
November: 91000,
December: 21000

```

}

I need to create a new hash called quarters with the total number amount of every trimester. This would be the output: `{"Q1"=>49000, "Q2"=>111000, "Q3"=>87200, "Q4"=>133500}`

This is the best I could do:

```
Q1 = sales[:January] + sales[:February] + sales[:March]
Q2 = sales[:April] + sales[:May] + sales[:June]
Q3 = sales[:July] + sales[:August] + sales[:September]
Q4 = sales[:October] + sales[:November] + sales[:December]

quarters = {
    "Q1"=> Q1,
    "Q2"=> Q2,
    "Q3"=> Q3,
    "Q4"=> Q4
}

```

The result is fine. 
My question is, which are better and simpler ways to do this? 
Please explain your answer. Thank you all.