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

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Answer 1 · 2017-07-04T11:12:37

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

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!

How do you solve 3a - 2b = 83a - 2b = 8 and 4a + b = 74a + b = 7 using substitution?