If x + y = 12, y + z = 15 and x + z = 18, then find x + y + z =?

  1. 18
  2. 12
  3. 15
  4. 22.5

Answer (Detailed Solution Below)

Option 4 : 22.5
Free
RRB NTPC CBT-I Official Paper (Held On: 4 Jan 2021 Shift 1)
5.5 Lakh Users
100 Questions 100 Marks 90 Mins

Detailed Solution

Download Solution PDF

Given:

x + y = 12, y + z = 15, x + z = 18

Calculation:

x + y = 12      ----(1)

y + z = 15      ----(2)

x + z = 18      ----(3)

By solving equations (1) and (2)

⇒ x – z = -3      ----(4)

By solving equations (3) and (4)

⇒ x = 7.5

Put the value of x in equation (1)

⇒ y = 4.5

Put the value of y in equation (2)

⇒ z = 10.5

x + y + z

⇒ 7.5 + 4.5 + 10.5

⇒ 22.5

∴ The value of x + y + z is 22.5.

Shortcut Trick

Add (1), (2) and (3)

⇒ 2(x + y + z) = 45     

⇒ (x + y + z) = 45/2 = 22.5

∴ The value of x + y + z is 22.5.

Latest RRB NTPC Updates

Last updated on Jun 11, 2025

-> RRB NTPC 2025 Exam Postponed. Railway Recruitment Board has rescheduled the RRB NTPC Exam for June 5, 2025 (Shift 3). 

-> RRB NTPC Exam Analysis 2025 is LIVE now. All the candidates appearing for the RRB NTPC Exam 2025 can check the complete exam analysis to strategize their preparation accordingly. 

-> The UPSC Prelims Result 2025 and UPSC IFS Result 2025 has been released @upsc.gov.in

-> The RRB NTPC Admit Card 2025 has been released on its official website.

-> Candidates who will appear for the RRB NTPC Exam can check their RRB NTPC Time Table 2025 from here.

-> The RRB NTPC CBT 1 Exam is scheduled from 5th June to 24th June 2025 as per the revised tentative exam schedule. 

-> The RRB NTPC 2025 Notification has been released for a total of 11558 vacancies.

-> A total of 3445 Vacancies have been announced for Undergraduate posts like Commercial Cum Ticket Clerk, Accounts Clerk Cum Typist, Junior Clerk cum Typist & Trains Clerk.

-> A total of 8114 vacancies are announced for Graduate-level posts in the Non-Technical Popular Categories (NTPC) such as Junior Clerk cum Typist, Accounts Clerk cum Typist, Station Master, etc.

-> Prepare for the exam using RRB NTPC Previous Year Papers.

-> Check out the Rajasthan PTET Admit Card 2025 and UPSC Prelims Result Date 2025 here.

Get Free Access Now
Hot Links: teen patti plus teen patti cash teen patti master app