Answer:
the answer is c, x=5
Explanation:
now, if we look at the pic, there is already one angle given.
and we know that sum interior angles of a triangle must be 180;
so the sum of the other two angles is: angle 2 +angle 3=180-60.
now, let's pick any number and put it into x.
first, if we put 15 into x: 7(15)+5=120,
so 180-(120+60)=0. and for there is another angle, it is invalid.
if we put 6: 7(6)+5=47,
180-(60+47)=73.
let's look at the third angle.
for x=6, the angle UBI is 120°. and we also know that the sum of angles on a horizontal line is always 180°, so 180-120=60, and for the third angle is NOT 73°, this one is also invalid.
if x=5: 7(5)+5=40, 180-(60+40)=80.
the angle UBI= 100°, 180-100=80°;
for 80°+60°+40° equals 180°, the answer c is correct.