Substitution is a method for solving systems of equations that involves solving for one variable in one equation and then substituting that value into the other equation.
Here's how we can use substitution to solve the system of equations:
5x+y=9
10x−7y=−18
Solve one equation for one variable, for example:
y = 9 - 5x
Substitute this expression of y into the other equation:
10x - 7(9 - 5x) = -18
Solve the equation resulting from the substitution
10x - 63 + 35x = -18
45x = 45
x = 1
Substitute this value of x back into one of the original equations to find the value of y.
5(1) + y = 9
y = 4
So the solution is (x,y) = (1,4)
You can check this solution by substituting it back into both original equations.