congruent means that they are identical looking at the order of the letters in the triangles EF are the last 2 and QR are the last 2 so EF should equal QR
we are told QR = 10 so EF needs to equal 10 so we have 6y+4 = 10
now solve for Y
6y +4 = 10 subtract 4 from each side: 6y = 6 divide each side by 6 y = 1
