What is the rectangular cross hatch chart used for eye test called

Whats the name of the vertical 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

Asquare picture with sides of 32 inches is to be mounted on a square mat with sides of 52 inches. find the area of the mat that will remain uncovered by the picture.