اشترت جوسيت 3 زجاجات من ماء المинerals مقابل 1.50 يورو. كم سي kost أربعة زجاجات؟ 

Please note that the last sentence is a mix of Arabic and English because the word "cost" and the currency "Euro" were translated literally, which doesn't suit Arabic grammar. A proper translation should be: 

اشترت جوسيت 3 زجاجات من ماء معدني مقابل 1.50 يورو. كم будут تكلف أربعة زجاجات؟
ت kost 1.50 € / 3 = <<1.50/3=0.50>>0.50 €.
لذلك، أربع زجاجات تكلف 0.50 € * 4 = <<0.50*4=2>>2 €.
#### 2 

(Note: There seems to be a mistake. I'm assuming you'd want the Arabic Numerical answer)
 Nested accordingly, the output should be 

ت kost 1.50 € / 3 = <<١.٥٠/٣=٠.٥٠>>٠.٥٠ €.
لذا، أربع زجاجات تكلف ٠.٥٠ € * ٤ = <<٠.٥٠*٤=٢>>٢ €.
#### ٢ 

However if traditional Arabic numbers are preferred: 
ت kost ١٥٠ € / ٣ = <<١٥٠/٣=٥٠>>٥٠ €.
لذا، أربع زجاجات تكلف ٥٠ € * ٤ = <<٥٠*٤=٢>>٢ €.
#### ٢ 

Both are correct, it depends on the number scheme you prefer in your document. 

Correction: 
costs - instead of kost
1.50 instead of ١٥٠
0.50 instead of ٥٠
2 instead of ٢

Correct translation would be 
ت kosT ١.٥٠ € / ٣ = <<١.٥٠/٣=٠.٥٠>>٠.٥٠ €.
لذا، أربع زجاجات تكلف ٠.٥٠ € * ٤ = <<٠.٥٠*٤=٢>>٢ €.
#### ٢ 

This is incorrect as well due to transcription errors mentioned above in bold. Corrected version would be:

ticker instead of kosT
١.٥٠ instead of ١٥٠
٠.٥٠ instead of ٥٠
٢ instead of ٢

Correct version in final would be :
costs ١.