Solve the simultaneous equations 4x + 2y =20 and 8x + 6y =45

Let (1) be 4x + 2y =20 and (2) be 8x + 6y =45.First we want to eliminate either x or y so that we have an equation in terms of only one unknown. Lets eliminate x. If we multiply (1) by 2 we have2(4x + 2y) = 2(20) giving 8x + 4y =40. Now the x terms in both equations are the same. Next we subtract 2*(1) from (2) to give:(2) - 2*(1) : (8x + 6y) - (8x + 4y) = 45 - 40 giving 2y = 5. this can be rearranged to find y = 2.5.Finally, the the value for y can be substituted into either (1) or (2) to give the value of x: 4x + 2(2.5) =204x = 15x = 15/4 = 3.75

JR
Answered by Jade R. Maths tutor

2699 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Differentiate y = x^2 + 3x + 5


15 machines work at the same rate, 15 machines can complete an order in 8 hours, however 3 of the machines break down after 6 hours. The other machines continue until the order is complete. In total how many hours does EACH machine work? (3 mark question)


Factorise 3x^2+15x


The Tour de France is 2162miles long. A cyclist knows his average speed his 12.37 miles/hour from his previous races. For the Tour de France the cyclist knows he will cycle for 10 hours a day. Estimate how many days it will take him to complete the race.


We're here to help

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

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning