How do you solve $2 a = 8$ $2a=8$ and $a + b = 2$ $a+b=2$ using substitution?

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Answer 1 · 2017-02-10T04:28:54

If $2 a = 8 \to a = \frac{8}{2} = 4$ $2a=8->a=8/2=4$

In the second expression we may replace $a = 4$ $a=4$

$\to 4 + b = 2$ $->4+b=2$ now subtract $4$ $4$ on both sides:

$->cancel4-cancel4+b=2-4->b=-2$

How do you solve 2a=82a=82a=8 and a+b=2a+b=2a+b=2 using substitution?