4a + 6b=10
2a - 4b =12
what is 12a?

Hi!

4a + 6b = 10
2a - 4b = 12

First make both a terms equal
2a · 2 - 4b · 2 = 12 · 2
4a - 8b = 24

Subtract both expressions to cancel out the a term.
4a + 6b = 10
-4a - 8b = 24
14b = -14
b = -1

Now put the value in one of the equations and solve
2a - 4 · -1 = 12
2a + 4 = 12
2a = 8
a = 4

Since a = 4, 12a = 48.

The answer is 48

Hope this helps! :)