Solve using the substitution method. show your work. if the system has no solution or an infinite number of solutions, state this.
15x + 9y = 240
6x + 3y = 90

The answer is x = 10, y = 10.

Step 1: rearrange the second equation for y.
Step 2: substitute y from the second equation into the first equation.
Step 3. Calculate y.

Step 1.
The second equation is: 6x + 3y = 90
Divide both sides of the equation by 3:
(6x + 3y)/3 = 90/3
6x/3 + 3y/3 = 30
2x + y = 30
Rearrange the equation:
y = 30 - 2x

Step 2.
Substitute y from the second equation (y = 30 - 2x) into the first equation:
15x + 9y = 240
15x + 9(30 - 2x) = 240
15x + 270 - 18x = 240
15x - 18x = 240 - 270
-3x = -30
x = -30/-3
x = 10

Step 3.
Since y = 30 - 2x and x = 10, then:
y = 30 - 2 * 10
y = 30 - 20
y = 10

3 Teaspoon

Step-by-step explanation:

Each sheet of cake requires 0.75 teaspoon of baking soda.

Therefore, 1 whole cake will require x teaspoon of baking soda.

Expressing it as a ratio

A whole cake will need 3 teaspoon of baking soda.

Since the expressions are not provided, it is hoped that you will be able to learn from the above. You can comment if you need further help.