Tell whether the ratios form a proportion.
1 to 0.4 and 9 to 3.6

no?  cause one is negative and the other is positive and I'm guessing they both have to be the same

Step-by-step explanation:

3  =  x

x         3

These are fractions btw

Cross multiply:

3 * 3 = x * x

Simplifying

3 * 3 = x * x

Multiply 3 * 3

9 = x * x

Multiply x * x

9 = x2

Solving

9 = x2

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '-1x2' to each side of the equation.

9 + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0

9 + -1x2 = 0

Add '-9' to each side of the equation.

9 + -9 + -1x2 = 0 + -9

Combine like terms: 9 + -9 = 0

0 + -1x2 = 0 + -9

-1x2 = 0 + -9

Combine like terms: 0 + -9 = -9

-1x2 = -9

Divide each side by '-1'.

x2 = 9

Simplifying

x2 = 9

Take the square root of each side:

x = {-3, 3}