Serena is building a bookcase she cuts two pieces of wood from one board one piece is 1 7/8 feey long and another is 3.5 ft long qhat is the total change in the lenght of the originl board

 feet

Step-by-step explanation:

The total change is the sum of the length of two boards she cut.

First board length is 1  7/8th feet. Let's change to improper fraction:

1 7/8 = 15/8 feet

Second board lengrh is 3.5 feet, or 3  1/2 feet. Let's change to improper fraction:

3  1/2 = 7/2 feet

Let's add the two:

The change in original board is 43/8 feet

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional