4a + 6b = 10

2a - 4b = 12

What does 12a equal?

multiply second equation by 2 and rewrite

4a + 6b = 10

4a - 8b = 24

subtract equations

0 + 14b = - 14

14b = - 14

b = - 1

sub back into 4a + 6b = 10 to find the value of a

4a + 6 (-1) = 10

4a - 6 = 10

4a = 16

a = 4

therefore, 12a = 12*4

12a is 48