Answer:
x=-21
Explanation:
The difference of a number and 3 is x - 3 
The sum of the number and 5 is x + 5 
Twice the difference of a number and 3 is therefore 2(x - 3) 
Three times the sum of the number and 5 is therefore 3(x + 5) 
These last two terms are equal. In equation form this is: 
2(x - 3) = 3(x + 5)
2x - 6 = 3x + 15 
Get rid of the 3x on the right side by subtracting 3x from both sides and you have: 
-x - 6 = 15 
Get rid of the -6 on the left side by adding 6 to both sides to get: 
-x = 21 
You are trying to solve for +x. To change the left side of this equation to +x multiply 
both sides by -1 and you change the equation to: 
x = -21 
 
Hope this helps you to understand the problem.