Answer:
Just need points well I wish I was that smart
 
        
             
        
        
        
Simplifying
3x + 4 = 7 + -2x
Reorder the terms:
4 + 3x = 7 + -2x
Solving
4 + 3x = 7 + -2x
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '2x' to each side of the equation.
4 + 3x + 2x = 7 + -2x + 2x
Combine like terms: 3x + 2x = 5x
4 + 5x = 7 + -2x + 2x
Combine like terms: -2x + 2x = 0
4 + 5x = 7 + 0
4 + 5x = 7
Add '-4' to each side of the equation.
4 + -4 + 5x = 7 + -4
Combine like terms: 4 + -4 = 0
0 + 5x = 7 + -4
5x = 7 + -4
Combine like terms: 7 + -4 = 3
5x = 3
Divide each side by '5'.
x = 0.6
 Answer: x = 0.6
        
             
        
        
        
To be able to give the answer to this item, we are to represent first with any variables the amount he earns each weekend for mowing the same field. Also, we represent the number of weeks he had worked by the variable y. The total amount of money he will have after working for y weeks is,
 
                           T = xy
Since, we are not given with any other information of the other expenses that have to be paid  then we can say that if T is already equal to the price of the new lawnmower then, Tom will be able to purchase it and begin his lawn mowing business in due time. 
        
             
        
        
        
Dy/dx = y/(x^2)
dy/y = dx/(x^2)
int[dy/y] = int[dx/(x^2)] ... apply integral to both sides
ln(|y|) = (-1/x) + C
|y| = e^{(-1/x) + C}
|y| = e^C*e^(-1/x)
|y| = C*e^(-1/x)
y = C*e^(-1/x)
So you have the correct answer. Nice job.
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Check:
y = C*e^(-1/x)
dy/dx = d/dx[C*e^(-1/x)]
dy/dx = d/dx[-1/x]*C*e^(-1/x)
dy/dx = (1/(x^2))*C*e^(-1/x)
is the expression for the left hand side (LHS)
y/(x^2) = [C*e^(-1/x)]/(x^2)
y/(x^2) = (1/(x^2))*C*e^(-1/x)
is the expression for the right hand side (RHS)
Since LHS = RHS, this confirms the solution for dy/dx = y/(x^2)
        
             
        
        
        

Or, if that hyphen between the lower index and 3 is actually a negative sign, then the sum is -189.