SOLUTION: 12a-5b=18 15a-5b=30

Question 169066: 12a-5b=18
15a-5b=30
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
12a-5b=18
15a-5b=30
.
Using the "elimination method", multiply the top equation by -1 and then combine both equations:
-12a+5b=-18
15a-5b= 30
-----------
3a = 12
a = 4
.
Using the above, substitute it back into either equation (I'll use the first one) and solve for 'b':
12a-5b=18
12(4)-5b=18
48-5b=18
-5b=-30
b= 6
.
Solution:
a = 4
b = 6

RELATED QUESTIONS
How do you solve by the addition-or-subtraction method. 12a-5b=18... (answered by jojo14344)

solve by the addition-or-subtraction method: 12a-5b=18 and... (answered by ewatrrr)

can you please help me solve by the addition-or-subtraction method: (((12a-5b=18... (answered by checkley77)

I'm 46 years old and working on refreshing my skills. How do I solve this using the... (answered by pallavi)

This is a last Subsitution question, but this one says solve by either ;addition or... (answered by checkley71,oscargut)

-20b 2nd power/3a times 15a 3rd... (answered by MathLover1)

21a^2b^6 + 15a^7b^3 � ab ___________________ 54a^5b^2 (answered by Fombitz)

subtract:4a-7ab+3b+12 from... (answered by tutor_paul)

simplify 15+16a/5b. Ive narrowed it down to... (answered by richwmiller)