find value of x and y
4.)2x-3y=-15
x=4y

[tex]\left\{\begin{array}{ccc}2x-3y=-15\\x=4y\end{array}\right\\\\substitute\\\\2\cdot4y-3y=-15\\8y-3y=-15\\5y=-15\ \ \ \ \ |both\ sides\ :5\\y=-3\\\\x=4\cdot(-3)=-12\\\\Solution:x=-12\ and\ y=-3.[/tex]

2x - 3y = -15x = 4ysubstitute x frm eq2 to eq12 (4y) - 3y = -158y - 3y = -155y = - 15y = -3substitute y in eq2x = 4(-3)x = -12y = -3 , x = -12