Question

How do you solve `x = y + 3` and `2x + y = 9` using substitution?

Answer 1

You are given 2 variables, decide which variable you want to be substituted and what equation will be your base equation to plug in your value.

Explanation:

1, In this case, `2x + y =9` may be use as your base equation and `x=y+3`, since this equation does not need rearrangement to find the value of `x`, will be used to substitute (for x from your base equation) to find the value of `y`;
2. From your base equation, substitute the value of `x`;
`2color(red)x +y=9`; where `x=y+3` forming like this
`2color(red)((y+3))+y=9`
3. Now, as reflected above, you have only one variable and you can now find the value `y`;
4. Then simplify the equation and combine like terms if applicable until you can arrive the value of y;
`2(y+3)+y=9`
`2y +6+y=9`
`3y+6=9`
5. Isolate the term with `y` from the numerical value by subtracting 6 both sides of the equation;
6. The value of y = 1
7. To find the value of `x`, you can use either of the equations and plug in the value of `y`;
8. Always remember to plug in values of `y` and `x` to check if both sides of the 2 equations are balanced.