Using the Triangle Sum Theorem, find x and the missing angles (2x +1) (5x +5) x= Angle (2x+1) = Angle (5x+5) =

x = 12

(2x + 1)° = 25°

(5x + 5)° = 65°

Step-by-step explanation:

By the property of a triangle,

Sum of all angles of a triangle is 180°

In the given right triangle,

(2x + 1)° + 90° + (5x + 5)°= 180°

7x + 96 = 180

7x = 180 - 96

x =

x = 12

Angle (2x + 1)° = 2(12) + 1 = 25°

Angle (5x + 5)° = 5(12) + 5 = 65°

Therefore, all three angles of the right triangle are 25°, 90° and 65°.

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 ☺

i think the answer is c sorry if it's wrong