Equation 1: 4a + 6b = 10
Subtract 6b on the right side of the equation
4a = 10 - 6b
Divide 4 on the right side of the equation, leaving the variable all by itself
a = 10 - 6b / 4
a = (5 - 3b) / 2
Equation 2: 2a - 4b = 12
Substitute (5 - 3b) / 2 for 'a' in the second equation
2(5 - 3b) / 2)) - 4b = 12
Combine like terms
5 - 3b - 4b = 12
5 - (-7b) = 12
Subtract 5 to both sides
5 - 5 - (-7b) = 12 - 5
-7b = 7
Divide -7 to both sides
-7b / -7 = 7 / -7
b = -1
Substitute -1 for 'b'
2a - 4(-1) = 12
2a + 4 = 12
Subtract 4 to both sides
2a + 4 - 4 = 12 - 4
2a = 8
Divide 2 to both sides
2a / 2 = 8 / 2
a = 4
12a = ?
Substitute 4 for 'a'
12(4) = 48
12a = 48
