Algebra....HELP!!
posted by Theresa on .
Solve the elimination method
7a + 6b = 3
7a +b = 25
The solution of the system is?

7a + 6b = 3
7a + b = 25
b = 7a + 25
Solve for a
7a + 6(7a + 25) = 3
7a + 42a + 150 = 3
49a + 150 = 3
49a = 147
a = 3
Solve for b
7(3) + b = 25
21 + b = 25
b = 4
Check answers
7a + 6b = 3
7(3) + 6(4) = 3
21 + 24 = 3
7a + b = 25
7(3) + 4 = 25
21 + 4 = 25
Answers:
a = 3
b = 4 
7 a + 6 b = 3
+
7 a + b = 25
________________
7 a + (  7 a ) + 6 b + b = 3 + 25
7 b = 28 Divide both sides by 7
7 b / 7 = 28 / 7
b = 4
7 a + 6 b = 3
7 a + 6 * 4 = 3
7 a + 24 = 3 Subtract 24 to both sides
7 a + 24  24 = 3  24
7 a =  21 Divide both sides by 7
7 a / 7 =  21 / 7
a =  3
Proof :
7 a + b = 25
 7 * (  3 ) + 4 = 25
21 + 4 = 25