Question

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

Answer 1

If you want to find the value of a, or of 12a, you'll need to eliminate the variable b.  Try this:  Multiply the first equation by 4 and the second by 6.  You'll get 24b-24b=0.  Solve for a.  Then mult. a by 12, to obtain 12a and its numeric value.