Examine this system of equations. Which is an equivalent form of the first equation that when added to the second equation eliminates the x terms?

4/5x - 3/5 y = 18
8x + 3y = 9

A. –8x + 6y = –180
B. 8x – 6y = 180
C. –8x + 3y = –90
D. 8x – 3y = 90

plz help, i really need help! i will give brainliest!

The answer is Option A

Step-by-step explanation:

To eliminate the x terms by adding the first to the second equation, we have to make the coefficient of the first x the additive inverse of the second.

i.e. we have to convert ⅘ into -8 which is the additive inverse of 8..

to convert ⅘ into -8 ..we multiply by -10

(⅘x × -10) - (⅗y × -10) = 18 × -10

; -8x + 6y = -180

So therefore if you add -8x to 8x, it would be equal to 0.

so, converting firstly the mixed fractions to improper fractions and then "adding".

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 ☺