Look up online "equation calculator" and it should be the first one to appear, "Symbolab" supper easy way to help you with problems!

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.

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

- Multiply 3 times
.

- Add
to 4y.

- Add
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.


- Add
to
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.

In this question, the profit of the restaurant after t months is given by a polynomial function. To find when it begins to show a profit, we find the numerical values of the function for t, and it shows a profit when 
Profit after t months:

0 months:
This is P(0). So

1 month:
This is P(1). So

2 months:
This is P(2). So

3 months:
This is P(3). So

4 months:
This is P(4). So

5 months:
This is P(5). So

6 months:
This is P(6). So

7 months:
This is `P(7). So

After 7 months it shows profit, so it starts showing profit on the 6th month, and thus, the correct answer is given by option D.
For another example of a function involving numeric value, you can check brainly.com/question/24231879
Since the vertex is at (-3, 6), the equation is given by
y = a(x + 3) + 6
Therefore, option A is the correct answer.
(300 box/h) * (0.8 cup/box) * (1 gal)/(16 cup) = 300*0.8/16 gal/h
.. = 15 gal/h
Jim's factory needs 15 gallons of juice per hour.