Question

Solve these simultaneous equations and explain how you worked your answer out

а) x+y=24
y=2x

b)2x+y=100
y=2(x-10)

c)x+y=26
3x+y=56

Answer 1

a)

x+y=24---1

y= 2x ---2

subs 2 in 1

x+2x=24

3x=24

x=8

when x=8 subs in 2

y=2(8)

y=16

b)

2x+y=100---1

y=2(x-10)---2

subs 2 in 1

2x+2(x-10)=100

2x+2x-20=100

2x+2x=100+20

4x=120

x=30

when x=30 subs in 2

y=2(30-10)

y=2(20)

y=40

c)

x+y=26---1

3x+y=56---2

from 1

x+y=26

y=26-x---3

subs 3 in 2

3x+26-x=56

3x-x=56-26

2x=30

x=15

when x=15 subs in 3

y=26-15

y=11