Nellie and her younger sister debbie share expenses on a holiday. nellie spends $122 more than debbie. their total expenses amount to $840.

a) write a pair of linear equations to represent the information given above.

b)explain how you can change this pair of equations to a linear equation in one unknown.

c)apply your method to find how much debbie spends on the holiday. show your work.

see below

Step-by-step explanation:

Let N = how much Nellie spends

Let D = how much Debbie spends

Part A

Nellie spends $122 more than Debbie.

N= D +122

Their total expenses amount to $840.

N+D =840

The two equations are

N= D +122

N+D =840

Part B

We can substitute the first equation which is solved for N into the second equation.  Every place we see an N in the second equation, we replace it with D+122

Part C

N= D +122

N+D =840

(D+122) +D = 840

Combine like terms

2D +122 = 840

Subtract 122 from each side

2D+122-122=840-122

2D =718

Divide by 2

2D/2= 718/2

D =359

Debbie spends 359

answer is 144

step-by-step explanation:

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.