If the angles are congruent, then:
5x + 2 = x + 50 {set the measurements equal to each other}
4x + 2 = 50 {subtrated x from both sides}
4x = 48 {subtracted 2 from both sides}
x = 12 {divided both sides by 4}
m<4 = 5x + 2
= 5(12) + 2 {substituted 12, in for x, into 5x + 2}
= 60 + 2 {multiplied 5 by 12}
= 62° {added}