how do u do this?

The dashes mean the sides are equal, so the angles opposite them are also equal, both = x.
So the angle next to the 118 angle is 180- 2x, and they add up to 180.
You have 118 + (180-2x) = 180
118 - 2x = 0
x = 59 degrees.

Isoceles triangle x + x = 118<-------------exterior angle

x = 54 degrees

The dashes mean that those two sides are of equal length. (The un-dashed side may be the same length, or not.)

I'm not sure what topics you are studying, so I can't advise you as to the solution that your instructor wants. But I will give you a helpful clue: the unmarked angle next to the 118 degree angle must be 62 degrees, as 118 + 62 must equal 180 degrees.

The dashes show that the sides are of equal length.