Question

2x-5y=-28 3x+15y=3 Solve by Substitution

Answer 1

Answer:

The value of x is -9 and y is 2.

Step-by-step explanation:

Given equation are

       $2x-5y=-28----(1) \\ \\ 3x+15y=3 ----(2)$

To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

From equation (1)

                    $2x-5y=-28\\ \\ 5y=2x+27\\ \\ y=\frac{2x+28}{5}----(3)$

Substituting the value of y in equation (2), we get the value of x

    $3x+15y=3\\ \\ 3x+15(\frac{2x+28}{5} )=3\\ \\ 3x+3(2x+28)=3\\ \\ 3x+6x+84=3\\ \\ 3x+6x=3-84\\ \\ 9x=-81\\ \\ x=\frac{-81}{9} \\ \\ x=-9$

Substituting the value of x in equation (3) , we get

$y=\frac{2x+28}{5} \\ \\ y=\frac{2\cdot(-9)+28}{5}\\ \\ y=\frac{-18+28}{5} \\ \\ y=\frac{10}{5} \\ \\ y=2$