Respuesta :

Distributive property. 

7*d - 7*2

7d - 14 = 5*d + 5*2

7d - 14 = 5d + 10
-5d          -5d

2d - 14 = 10
     +14    +14

2d = 24

2d/2 = 24/2

d= 12
7(d-2)=5(d+2)
first you use distributive property and time seven with d and 2
7d - 14 = 5(d+2)
second you do the same with 5 you times it with d and 2 
7d - 14 = 5d + 10
third you add fourteen to itself then to the other side of the equation 
7d = 5d + 24
fourth you minus 5d to itself and to the other side of the equation 
2d = 24
fifth you divide 2 with itself then the other side of the equation
d = 12
d = 12 is your answer
welcome :/