How do i use substitution to solve each system?

y= 0.8x + 7.2
20x + 32y=48

I would rearrange them to know what I had.

0.8x - y = -7.2
20x +32y = 48

Then I would consider taking out the largest factor I could in the second equation. That would be a factor of 4.

For solving by substitution, I would solve the first equation for y which would be -y = -7.2 - 0.8x or
y = 7.2+0.8x

Substitute this value for y into the second equation and go from there.

your first equation tells you what y is, so sub that into the second

20x + 32(.8x+7.2) = 48

solve for x, then sub that x value back into the first equation to get y.

To solve a system of equations using the substitution method, follow these steps:

1. Solve one of the equations for one variable in terms of the other variable. In this case, the first equation is already solved for y, so we can leave it as it is.
Equation 1: y = 0.8x + 7.2

2. Substitute the expression found in step 1 into the other equation, replacing the variable you solved for. Substitute y in the second equation with the expression (0.8x + 7.2).
Equation 2: 20x + 32(0.8x + 7.2) = 48

3. Simplify and solve the resulting equation for the remaining variable.
20x + 25.6x + 230.4 = 48
45.6x + 230.4 = 48
45.6x = 48 - 230.4
45.6x = -182.4
x = -182.4 / 45.6
x ≈ -4

4. Substitute the value of x back into one of the original equations (Equation 1) and solve for the other variable.
y = 0.8(-4) + 7.2
y = -3.2 + 7.2
y ≈ 4

5. The solution to the system of equations is x ≈ -4 and y ≈ 4.

Using substitution, we found that the solution to the system of equations is x ≈ -4 and y ≈ 4.