With substitution! (with pictures-2 separate questions) !

Explanation contains answer.

Step-by-step explanation:

Question 1:

I would perfer to solve the first equation for y because there is only one operation to perform on both sides and it is subtraction of 2x on both sides.

The other equation requires two steps to isolate y; subtracting 3x on both sides then multiplying both sides by -1.

So basically solving the first one for y because it has coefficient 1.

Question 2:

They solved the 2nd equation for y and plugged into itself instead of plugging it into 1st equation.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x