l Use Substitution to solve c + s = 300 and 3c + 1.5s = 825

Enter Equation 1

Enter Equation 2

    

Use the substitution method to solve:

c + s = 300

3c + 1.5s = 825

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:

3c + 1.5s = 825

Subtract 1.5s from both sides to isolate c:

3c + 1.5s - 1.5s = 825 - 1.5s

3c = 825 - 1.5s

Now divide by 3:

3c
3
=
  
825 - 1.5s
3

Revised Equation 2:

c  =  825 - 1.5s
  3

Plug Revised Equation 2 value into c:

1(c) + s = 300

1 * ((825 - 1.5s)/3) + s = 300

((825 - 1.5s)/3) + s = 300

Multiply equation 1 through by 3

3 * (((825 - 1.5s)/3) + s = 300)

3 * (((825 - 1.5s)/3) + s = 300)

825 - 1.5s + 3s = 900

Group like terms:

-1.5s + 3s = 900 - 825

1.5s = 75

Divide each side by 1.5

1.5s
1.5
=
  
75
1.5

s  =  75
  1.5

s = 50

Plug this answer into Equation 1

1c + 1(50) = 300

1c + 50 = 300

1c = 300 - 50

1c = 250

Divide each side by 1

1c
1
=
  
250
1

c  =  250
  1

c = 250

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