SOLUTION: I don't understand what to do on this Solve using whatever method you prefer: 5c/4 + d = 11/2 c + d/3 = 14/15

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: I don't understand what to do on this Solve using whatever method you prefer: 5c/4 + d = 11/2 c + d/3 = 14/15      Log On


   

Question 835281: I don't understand what to do on this
Solve using whatever method you prefer:
5c/4 + d = 11/2
c + d/3 = 14/15
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
This could be easier if use substitution. Maybe first multiply the first equation by 2, and the second equation by 15... you still might be able to use Elimination.

%285c%2F4%292%2B2%2Ad=11
5c%2F2%2B2d=11
%285%2F2%29c%2B2d=11
One more step, multiply by 2 b.s.
5c%2B4d=22
-
15c%2B%28d%2F3%2915=14
15c%2B5d=14

I really am more interested in using Elimination Method. The system is now displayable as:
5c%2B4d=22 and 15c%2B5d=14.
Multiplying the first of these by 3 on both sides, our system is:
15c%2B12d=66 and 15c%2B5d=14
READY TO ELIMINATE c.

Continuing with Elimination Method,
%2815c%2B12d%29-%2815c%2B5d%29=66-14
15c-15c%2B12d-5d=52
7d=52
highlight%28d=52%2F7%29 or highlight%28d=7%263%2F7%29
-
Return to almost any equation you want, find c and plug in the value for d.
c = 14/15-d/3
c=14/15-(52/7)/3
c=14/15-52/21, lcd is 3*5*7
c=(14/15)(7/7) - (52/21)(5/5)
c=(98-260)/105
c=-162/105=-54/35
highlight%28c=-%2854%2F35%29=-1%2619%2F35%29

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

I don't understand what to do on this
Solve using whatever method you prefer:
5c/4 + d = 11/2
c + d/3 = 14/15


5c%2F4+%2B+d+=+11%2F2 ----- eq (i)

c+%2B+d%2F3+=+14%2F15 ------ eq (ii)

Multiply eq (i) by 12 to create eq (iii)

Multiply eq (ii) by 15 to create eq (iv)

Subtract eq (iv) from eq (iii) or vice-versa to determine the value of "d"

Substitute value of "d" into any of the 4 equations to determine the value of "c"

Then do a check!! 



If you need a complete and detailed solution, let me know!!



Send comments, “thank-yous,” and inquiries to “D” at MathMadEzy@aol.com.

Further help is available, online or in-person, for a fee, obviously.