Use Substitution to solve m + s = 20 and 3m + 8s = 100
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Use the substitution method to solve:
m + s = 20
3m + 8s = 100
Check Format
Equation 1 is in the correct format.
Check Format
Equation 2 is in the correct format.
Rearrange Equation 2 to solve for m:
3m + 8s = 100
Subtract 8s from both sides to isolate m:
3m + 8s - 8s = 100 - 8s
3m = 100 - 8s
Now divide by 3:
3m
3
=
100 - 8s
3
Revised Equation 2:
m =
100 - 8s
3
Plug Revised Equation 2 value into m:
1(m) + s = 20
1 * ((100 - 8s)/3) + s = 20
((100 - 8s)/3) + s = 20
Multiply equation 1 through by 3
3 * (((100 - 8s)/3) + s = 20)
3 * (((100 - 8s)/3) + s = 20)
100 - 8s + 3s = 60
Group like terms:
-8s + 3s = 60 - 100
-5s = -40
Divide each side by -5
-5s
-5
=
-40
-5
s =
-40
-5
s = 8
Plug this answer into Equation 1
1m + 1(8) = 20
1m + 8 = 20
1m = 20 - 8
1m = 12
Divide each side by 1
1m
1
=
12
1
m =
12
1
m = 12
What is the Answer?
m = 12 and s = 8
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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