Answer:
In the picture above. 
Step-by-step explanation:
Using some identities for solution 
I hope that it's a clear solution. 
 
        
             
        
        
        

Solve the following using Substitution method
2x – 5y = -13
3x + 4y = 15


- To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

- Choose one of the equations and solve it for x by isolating x on the left-hand side of the equal sign. I'm choosing the 1st equation for now.

- Add 5y to both sides of the equation.


- Multiply  times 5y - 13. times 5y - 13.

- Substitute  for x in the other equation, 3x + 4y = 15. for x in the other equation, 3x + 4y = 15.

- Multiply 3 times  . .

- Add  to 4y. to 4y.

- Add  to both sides of the equation. to both sides of the equation.

- Divide both sides of the equation by 23/2, which is the same as multiplying both sides by the reciprocal of the fraction.

- Substitute 3 for y in  . Because the resulting equation contains only one variable, you can solve for x directly. . Because the resulting equation contains only one variable, you can solve for x directly.


- Add  to to by finding a common denominator and adding the numerators. Then reduce the fraction to its lowest terms if possible. by finding a common denominator and adding the numerators. Then reduce the fraction to its lowest terms if possible.

- The system is now solved. The value of x & y will be 1 & 3 respectively.

 
        
             
        
        
        
9 + 5 + 4 + 7 = 25
Ratio = 5 : 25
Ratio = 1 : 5 <==== answer
 
        
             
        
        
        
Answer: It's 48%. See below. 
Step-by-step explanation:
By definition, percent means out of a hundred. For instance, 10 percent is 10 out of 100. 
One way to make  a percent is by making the denominator 100. In order to do so, multiply the numerator and the denominator by 4, since 25 times 4 is 100.
 a percent is by making the denominator 100. In order to do so, multiply the numerator and the denominator by 4, since 25 times 4 is 100. 
 =
  =   = 48 %
 = 48 %
This is very simple, and mental math is definitely possible. Hope this help.