Given 4x+7y=25 and 2x+5y=17, identify x and y by solving the simultaneous equations

First thing we have to do is to eliminate one of the variables, either x or y (it doesn’t matter which one). In order to achieve that, we aim to have the same co-efficient (number in front of x or y) of a variable in both equations.

In this example, we can observe that no co-efficient is the same so we have to do some manipulation first before eliminating a variable!

Multiplying 2x+5y=17 by 2, give us 4x+10y=34 (Remember to multiply by 2 all the numbers)

Now that we have the same x co-efficient in both equations we can eliminate the x variable by subtracting one equation from the other:

    4x + 10y = 34

–  4x + 7y = 25



Hence, we can substitute y in one of the initial equations e.g. 2x+5y=17

2x+5(3) = 17




Therefore, the variables are x=1 and y=3

Andreas O. GCSE Chemistry tutor, GCSE Maths tutor, GCSE Physics tutor

11 months ago

Answered by Andreas, a GCSE Maths tutor with MyTutor

Still stuck? Get one-to-one help from a personally interviewed subject specialist


£20 /hr

Sam F.

Degree: Economics with Placement (Bachelors) - Bath University

Subjects offered:Maths, Physics+ 2 more

Extended Project Qualification

“Studying for BSc Hons Economics, A level economics, maths and physics. Able to tutor GCSE/AS/A2 Economics, Maths and GCSE physics! ”

£20 /hr

Upasana T.

Degree: Medicine (Bachelors) - Birmingham University

Subjects offered:Maths, Latin+ 1 more


“About me: Hi, my name is Upasana Topiwala and I am currently in my third year of medical school at the university of Birmingham. I've taken up tutoring in order to inspire my students to appreciate the importance of science in our liv...”

Sahil M. A Level Biology tutor, GCSE Biology tutor, A Level Chemistry...
£20 /hr

Sahil M.

Degree: Medicine (Bachelors) - Manchester University

Subjects offered:Maths, Spanish+ 3 more

-Medical School Preparation-

“Hello! My name is Sahil and I am currently a medical student at the University of Manchester. I am really looking forward to tutoring you in Spanish, Chemistry, Biology or Maths as well as trying to help you during the difficult proce...”

About the author

Andreas O.

Currently unavailable: for new students

Degree: Medicinal and Biological Chemistry (MChem) (Masters) - Edinburgh University

Subjects offered:Maths, Physics+ 2 more


“Hey there!! My name is Andreas and I study Medicinal and Biological Chemistry (MChem) at University of Edinburgh (UoE). I consider myself passionate in the field of Science and Maths and at the same time I try to learn more and become ...”

MyTutor guarantee

You may also like...

Posts by Andreas

Given 4x+7y=25 and 2x+5y=17, identify x and y by solving the simultaneous equations

What is the volume of carbon dioxide released at room temperature and pressure when 6.2 g of copper carbonate reacts with excess dilute sulfuric acid?

Other GCSE Maths questions

Make y the subject of the formula x=(2y-1)/(4-y)

Solve the simultaneous equations: 2x + 3y = 28 and x + y = 11

Dipen and Nisha are planning a wedding reception. Nisha says, “I want to invite 70 guests.” Dipen says, “If we invite one-fifth fewer guests, we will save more than £500” Is Dipen correct?

How do I find the roots and and coordinates of the vertex of the graph y = 2x^2 + 4x - 8 ?

View GCSE Maths tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss