x+3=-10

  -3    -3          Additive Inverse Property

    x=-13

x+3=-10       Rewrite original equation

-13+3=-10    Plug in answer to check

-10=10         Both sides are the same

4x-5=19

   +5  +5  Add 5 to both sides to cancel out subtract 5

4x=24

/4   /4      Divide 4 on both sides to cancel multiply 4

x=6

4x-5=19    Rewrite original equation

4(6)-5=19 Plug in your answer to check for validity

24-5=19    Simplify both sides using PEMDAS

19=19      Answer is the same on both sides!

9r + 15 = 87

9r + 15 = 87

     -15    -15  Subtract 15 to cancel +15

9r=72            

/9  /9            Divide 9 both sides to cancel multiply 9

r=8

9r+15=87      Rewrite original equation

9(8)+15=87   Plug in answer to check

72+15=87      Simplify using PEMDAS

87=87           Both sides are equal

b/13+12=19

       -12   -12   Subtract 12 to cancel out +12

b/13=7

*13    *13         Multiply by 13 to cancel out divide 13

b=91

b/13+12=19    Rewrite original equation

91/13+12=19   Plug in answer to check

7+12=19          Simplify using PEMDAS

19=19              Both sides are true

3-7m = 24

-3         -3     Subtract 3 to cancel out the positive 3

-7m=21

÷(-7) ÷(-7)   Divide by negative 7 to cancel out 

m=-3

3-7m=24       Rewrite original equation

3-7(-3)=24     Plug in answer to check

3+21=24       Simplify using PEMDAS

24=24          Both sides are equal