The two angles 2y and 4y-36 add up to 180 degrees since they form a straight angle (aka straight line). We'll use this to find y.
(2y) + (4y-36) = 180
2y + 4y-36 = 180
6y-36 = 180
6y-36+36 = 180+36
6y = 216
6y/6 = 216/6
y = 36
If y = 36, then 2y = 2*y = 2*36 = 72
The bottom right corner of the smaller triangle on the left has an angle of 72 degrees
Focus on this same triangle. It has angles 51 degrees (bottom left corner), 72 degrees (bottom right corner) and x degrees (top)
They add to 180 degrees
x+51+72 = 180
x+123 = 180
x+123-123 = 180-123
x = 57
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In summary,
x = 57
y = 36
