Answer:
b = -4
Explanation:
given, 3y + 12 = 6x ..........make y the subject
y = ( 6x - 12 ) / 3 ______eq 1
also given,
2y = 4x + b ........make y the subject
y = ( 4x + b )/ 2
using simultaneous equation:
( 4x + b )/ 2 = ( 6x - 12 ) / 3
12x + 3b = 12x - 24 ........x gets cancel out
3b = -24
b = -8