Use Substitution to solve 9c + 3s = 75 and 5c + 8s = 67
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Use the substitution method to solve:
9c + 3s = 75
5c + 8s = 67
Check Format
Equation 1 is in the correct format.
Check Format
Equation 2 is in the correct format.
Rearrange Equation 2 to solve for c:
5c + 8s = 67
Subtract 8s from both sides to isolate c:
5c + 8s - 8s = 67 - 8s
5c = 67 - 8s
Now divide by 5:
5c
5
=
67 - 8s
5
Revised Equation 2:
c =
67 - 8s
5
Plug Revised Equation 2 value into c:
9(c) + 3s = 75
9 * ((67 - 8s)/5) + 3s = 75
((603 - 72s)/5) + 3s = 75
Multiply equation 1 through by 5
5 * (((603 - 72s)/5) + 3s = 75)
5 * (((603 - 72s)/5) + 3s = 75)
603 - 72s + 15s = 375
Group like terms:
-72s + 15s = 375 - 603
-57s = -228
Divide each side by -57
-57s
-57
=
-228
-57
s =
-228
-57
s = 4
Plug this answer into Equation 1
9c + 3(4) = 75
9c + 12 = 75
9c = 75 - 12
9c = 63
Divide each side by 9
9c
9
=
63
9
c =
63
9
c = 7
What is the Answer?
c = 7 and s = 4
How does the Simultaneous Equations Calculator work?
Free Simultaneous Equations Calculator - Solves a system of simultaneous equations with 2 unknowns using the following 3 methods: 1) Substitution Method (Direct Substitution) 2) Elimination Method 3) Cramers Method or Cramers Rule
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