Ineed to know the strategy, the correct work, and to identify the error.

See below

Step-by-step explanation:

13x + 5 + 17x - 4.5 + x

NOTE: You can only add/subtract LIKE terms . Here we have  variable terms in x  (13x , 17x and x) and 2 constants ( 5 and 4.5).

Sarah's next line is

18x + 17x - 4.5 + x

This is incorrect . It looks like she  added 13x + 5 and got 18x!! Which is of course wrong because they are NOT LIKE terms. 5 is a constant and 13x is a variable term in x.

The third line is correct:-

35x - 4.5 + x.

She has added the 2 variables 17x and 18x.

Fourth line  is  30.5x + x. She's at it again - Trying to subtract 4.5 from 35x .

Last line 31.5x

She has added  the 2 terms in x correctly, but the final answer is wrong of course due to the earlier errors.

mr. flanders’ class sold 47 doughnuts and   mr. rodriquez’s class sold 38 cartons of milk

step-by-step explanation:

let x be the number of doughnuts sold by mr. flanders’ class and y be the number of cartons sold by mr. rodriquez’s class.

1. together, the classes sold 85 items, then

x+y=85.

2. both classes earn earned $104.49 for their school. if doughnuts were sold for $1.35 each, then x doughnuts costed $1.35x. if cartons of milk were sold for $1.08 each, then y cartons costed $1.08y. hence,

1.35x+1.08y=104.49.

3. solve the system of two equations:

squares, rhombus, rectangles