SOLUTION: Please help! im so confused! I have tried by substitution and elimination but i just cant get it!!! 2. t+m=2.1 2t+3m=5.15 3. 4o+5a=2.00 3o+4a=1.56 7. 2l+2w=160 2

Algebra ->  Expressions-with-variables -> SOLUTION: Please help! im so confused! I have tried by substitution and elimination but i just cant get it!!! 2. t+m=2.1 2t+3m=5.15 3. 4o+5a=2.00 3o+4a=1.56 7. 2l+2w=160 2      Log On


   

Question 126789: Please help! im so confused! I have tried by substitution and elimination but i just cant get it!!!
2. t+m=2.1
2t+3m=5.15
3. 4o+5a=2.00
3o+4a=1.56
7. 2l+2w=160
2.5r+8b=137
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
Problem 2.
Eq. 1 t%2Bm=2.1
Eq. 2 2t%2B3m=5.15
Multiply Eq. 1 by -2. That gives you -2t in Eq. 1 and 2t in Eq. 2
Eq. 1 -2t-2m=-4.2
Eq. 2 2t%2B3m=5.15
Now add the two equations
0t%2Bm=.95
m=.95
Now you can proceed either one of two ways. Either substitute the .95 value you got for m back into Eq. 1 (t%2B.95=2.1 => t=1.15), or you can start with the original 2 equations and multiply Eq. 1 by -3 so that the addition step will eliminate m.

Eq. 1 -3t-3m=-6.3
Eq. 2 2t%2B3m=5.15
========================
-t%2B0m=-1.15
t=1.15 Same result.

Problem 3.
Do this one the same way, except that you need to be a little more creative in finding the multipliers for the equations.
Eq. 1 4o%2B5a=2.00
Eq. 2 3o%2B4a=1.56

Multiply Eq. 1 by 3 and Eq. 2 by -4. That gives you 12o in Eq. 1 and -12o in Eq. 2. Then proceed as in the first problem.

Problem 7. There is no effective solution method for this system because you have 4 different variables and only 2 equations.