Answer:
A
Step-by-step explanation:
Using the sine ratio in the right triangle
sin40° =
=
= 
Multiply both sides by 7, thus
AC = 7sin40° → A
3x - 15 = 105
3x = 120
x = 40
3(40) - 15 + y + 24 = 180
120 - 15 + y + 24 = 180
129 + y = 180
y = 51
The internal angle sum of a quadrilateral is :
C. 360°
The sum of internal angles of a polygon is determined by a formula :

where n represents number of sides.
In a quadrilateral there are four sides,
So, plugging 4 in the formula :
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