Question

Solve for x and y if: 2x + 3y = 5 and 3x + 4y = 4

Answer 1

`\left\{\begin{array}{ccc}2x+3y=5&|\text{multiply both sides ny 3}\\3x+4y=4&|\text{multiply both sides by (-2)}\end{array}\right\\\underline{+\left\{\begin{array}{ccc}6x+9y=15\\-6x-8y=-8\end{array}\right}\qquad\text{add both sides of the equations}\\.\qquad\qquad \boxed{y=7}\\\\\text{put the value of y to the first equation}\\\\2x+3(7)=5\\\\2x+21=5\qquad\text{subtract 21 from both sides}\\\\2x=-16\qquad\text{divide both sides by 2}\\\\\boxed{x=-8}\\\\Answer:\ \boxed{x=-8\ and\ y=7}`