Question

Using substitution to solve the system x = 2y + 3 and 4x - 5y = 9, which of the following could be the first step?

x - 2y = 3
4x - 5y = 9


4(2y + 3) - 5y = 9


x + 2y = 4x - 5y


5x - 3y = 12


- 3x + 7y = -6

Answer 1

ok... you are told

x = 2y + 3

you need to substitute this into the equation

4x - 5y = 9

so replace x with 2y + 3

you would have

4(2y + 3) - 5y = 9