Write down d as a column vector

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

Reflect the point (7,0) across the y-axis

John used linear combination to solve the system of equations shown. he did so by multiplying the first equation by -3 and the second equation by another number to eliminate the x-terms. what number did jonas multiply the second equation by? 4x-6y=23x+5y=11