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The equation is 2x + 40 = 60. \ \

According to subtraction property of equality; if a = b, then .

       (Subtract 40 from each side).

                       (Additive inverse property: )

                              (Subtract: 60 - 40 = 20) \ \

According to division property of equality:

For any number a, b and c, If a = b then .

                        (Divide each side by 2)

                            (Cancel common terms)

x  = 10                              (Divide:)      

Check:

To check the solution, substitute x  = 10 in original equation. 

2x + 40 = 602(10) + 40 = 60  

20 + 40 = 60                           (Multiply: 2(10) = 20)

60 = 60                                   (Add: 20 + 40 = 60)

Compare the values, the equation is true.

The value of x  = 10.