Question

How do you solve `3a - 2b = 8` and `4a + b = 7` using substitution?

Answer 1

From the second equation you may infer: `b=7-4a`

Explanation:

Now substitute `b` in the first equation:

`3a-2(7-4a)=8->3a-14+8a=8->`

`3a+8a=8+14->11a=22->a=22/11=2`

`b=7-4*2=-1`

Check your answer:
`3*2-2*(-1)=6+2=8` check!
`4*2+(-1)=8-1=7` check!