Solve the simultaneous equations, 5x + 2y = 20 , x + 4y= 13

(Equation 1) 5x + 2y = 20 (Equation 2) x + 4y= 13
As we know the values for x and y are the same in both equations, we can use them to find out the values for both, In order to do this we need to take one equation and define it by either x or y, for example taking equation 2 and definining x in terms of y by rearranging the equation.
x + 4y = 13
x= 13 - 4y
Now we have x defined in terms of y we can put this into equation 1 and simplify to get a value for y.
5x + 2y = 20
5(13-4y) + 2y = 20
65 - 20y +2y = 20
65 - 18y = 20
-18y = -45
18y = 45
y = 2.5
Now that we have a value for y we can use that for find x. If we put our value for y into equation 2
x + 4y = 13
x + 4(2.5) = 13
x + 10 = 13
x = 3
Now we have our two values for x and y we have solved the simultaneous equations, to check they're correct we should substitute both values into either equation and see if the equation is correct.

EC
Answered by Ellen C. Maths tutor

11559 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Sarah asked 20 people at a tennis tournament how they travelled there. She found that 13 of them travelled by car. Estimate how many of the total 2000 people at the tournament travelled by car.


Issy goes to buy some fruit. She has been told by one friend that 2 apples and 3 bananas costs £3.80. She has been told by another friend that 5 apples and a banana costs £3.65. what are the individual costs of an apple and a banana?


How do I skecth a grpah of y = x^2 - 7x + 10?


Make X the subject of the equation (9x-7)/3 = 8y


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences