MATH - SCIENCE INTEGRATION

bullet1 SOLVING ONE STEP EQUATIONS

bullet2 Subtraction

x - a = b
Addition and subtraction problems are the same because you can change subtraction to addition and change the sign of the next number to the right to the opposite.


bullet3 Example 1

x - 19 = 10  
can be rewritten as x + (-19) = 10
 
Solve:  Add 19 to both sides of the equation  
                 x + (-19) + 19 = 10 + 19
 
Solution:  -19 + 19 = 0
                         so just x remains on the right hand side of the =
                   10 + 19 = 29 so 29 is on the left hand side of the =
                    x = 29
 
Check:  Substitute 29 in for x in the original equation.  x -19 = 10
                29 - 19 = 10 and 10 = 10 so 29  is the correct answer.


bullet3 Example 2

x - (- 23) = - 56
can be rewitten as   x + 23 = - 56
 
Solve:  Add - 23  to both sides of the equation
                  x + 23 + (- 23) = - 56 + (- 23)
 
Solution:  23 + (- 23) = 0
                        so just x remains on the right hand side of the =
                    - 56 + (- 23) = - 79 so - 79 is on the left hand side of the =
                   x = - 79
 
Check:  Substitute - 79 in for x in the original equation.  
                     x - (- 23) = - 56
               - 79 - (- 23) = -56 and -56 = - 56
                        so - 79  is the correct answer.


bullet3 Practice Exercises

Exercise 1:  x - 15 = 89
 
Exercise 2:  x - (-7.63) = -92.56
 
Exercise 3:  x - 6/11 = 4/15
 
Hit next to check your answers.


  • Solutions
    Exercise 1:  Rewrite the problem as x + (-15) = 89
                           Add 15 to both sides
                            x = 104
     
    Exercise 2:  Rewrite the equation as x + 7.63 = -92.56
                           Add -7.63 to both sides
                            x = -100.19
     
    Exercise 3:  Rewrite the equation as x + (-6/11) = 4/15
                           Add 6/11 to both sides
                          x = 134/165