Solve these simultaneous equations.....3a+2b = 17 and 8a-2b= 60

3a+2b = 178a-2b = 60We are going to solve this using the elimination method. This means that we are going to eliminate the variable (or letter) that has the same value in each equation. In this case it is the 'b' because both equations have '2b' in them. Using the SSS abbreviation, which stands for Same Sign Subtract, we can see that the '2b' actually has different signs in the two equations; in the top one it is positive, and in the bottom one it is a negative.With different signs, we therefore have to add the two equations, and this in turn will eliminate the 'b' variable. So if we add 8a+3a we get 11a, and if we get 60 + 17 we get 77. Lining up the variables and the equals sign we get 11a=77. Dividing both sides by 11 gives you a=7. You can then pick either equation to substitute this value back into. Taking the top equation; 3a+2b = 17, we can say 3(7) + 2b =17. Therefore 21 + 2b = 17. Subtracting 21 from both sides gives 2b=-4 and therefore b= -2. Those are your two answers

JO
Answered by Joel O. Maths tutor

5477 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Jorgen has 20 sweets in his pocket. The sweets are either blue or yellow. He picks a sweet and eats it and takes another sweet and eats it again. The probability of him picking two blue sweets is 6/30. How many yellow sweets does he have in his pocket.


White paint costs £2.80 per litre and blue paint costs £3.50 per litre. White and blue paint are mixed in the ratio 3 : 2. How much does it cost to make 18 litres of this mixture?


Solve this pair of simultaneous equations. 5x + 2y = 20 x + 4y= 13


What is Pythagorus' Theorem?


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