Question

Solve the system using substitution 8x+9y=15 5x-2y=17

Answer 1

$5x-2y=17\ \ \ \ |-5x\\-2y=-5x+17\ \ \ \ |:(-2)\\y=2.5x-8.5\\\\\text{substitute to the first equation}\\\\9x+9(2.5x-8.5)=17\ \ \ \ |\text{use distributive property}\\9x+22.5x-76.5=17\ \ \ \ |+76.5\\31.5x=93.5\ \ \ \ |:31,5\\x=3\\\\\text{substitute the value of x to the equation}\ y=2.5x-8.5\\\\y=2.5(3)-8.5=7.5-8.5=-1\\\\Answer:\ x=3,\ y=-1\to(3;\ -1)$