Solve for x.
A) -9
C) -5
B) -11
D) 10

here's the answer to your question

D. 10

Step-by-step explanation:

Concept:

Here, we need to know the triangle sum theorem.

The Triangle Sum Theorem states that the sum of the three interior angles in a triangle is always 180°.

If you are still confused, please refer to the attachment below for a graphical explanation.

Solve:

According to the Triangle Sum Theorem:

∠1 + ∠2 + ∠3 = 180

Substitute the angle values

(60) + (50) + (7x) = 180

Combine like terms

110 + 7x = 180

SUbtract 110 on both sides

110 + 7x - 110 = 180 - 110

7x = 70

Divide 7 on both sides

7x / 7 = 70 / 7

x = 10

Hope this helps!! :)

Please let me know if you have any questions

step-by-step explanation: so we look at the formula un = a + (n-1)d

un is the amount of seats

n is the nth term aka row number

a is the original sequence/row number

d is the difference between each term

so in this a=22 d=6 and n can remain as n because we are simply formjng a rule

lets put these in the equation

un=22+(n-1)(6)

this is your answer to part a

however

lets double check that this is correct, we'll try putting it into the second term

un=a+(n-1)d

u2=22+(2-1)(6)

u2=22+6

u2=28

as the question said the second row has 28 seats so now we know the formula we made is correct.

as for part b

un=a+(n-1)

its asking us to find a row with 100 seats.

remember un was the amount of seata so all we do is substitute this in.

un=100 a=22 d=6

un=a+(n-1)d

100=22+(n-1)(6)

so now we simplify to find n which is the row number.

100-22=22+(n-1)(6)-22

78=(n-1)(6)

78/6=(n-1)(6)/6

13=n-1

13+1=n-1+1

14=n

so now we know that in the 14th row there is 100 seats.

hope this and that you understood! its my first time using the app or anyone out on here : p its also me to revise so a bunch! ask more questions if you dont understand ☺