how to solve this cause I was gone for 1/2 of my class and missed stuff.

the answer is 58°

a triangle can only have 180 degrees

we already know the measure of two angles

28+30= 58

because the third angle (let's call it x) for a a straight line (180°) with y, we know that
x + y =180

180-58 = 122°
x = 122°
180 - 122 = 58
y = 58°