Write a numerical expression for the calculation.
Add 79, 139, and 19, and then divide by 27.

(79+139+19) / 27

answer is 8.77 repeating if you need it

Step-by-step explanation:

Proportion says that two ratios (or fractions) are equal.

Example: you want to draw the dog's head ... how long should it be?

proportion dog

Let us write the proportion with the help of the 10/20 ratio from above:

?42 =  1020

Now we solve it using a special method:

?/42 : 10/20

Multiply across the known corners,

then divide by the third number

And we get this:

? = (42 × 10) / 20  

= 420 / 20  

= 21

So you should draw the head 21 long.

Source: https://www.mathsisfun.com/algebra/proportions.html

Now, back to your question

20/5

a. 100/25

100 x 5 = 500

25 x 20 = 500

Both matches, so 100/25 is proportional to 20/5

b. 10/2

10 x 5 = 50

2 x 20 = 40

50 is not equal to 40, so 10/2 is not proportional to 20/5

c. 60/15

60 x 5 = 300

15 x 20 = 300

Both matches, so 60/ 15 is proportional to 20/5

d. 40/2

40 x 5 = 200

2 x 20 = 40

40 is not equal to 200, so 40/2 is not proportional to 20/5

e. 4/2

4 x 5 = 20

2 x 20 = 40

20 is not equal to 40, so 4/2 is not proportional to 20/ 5

In conclusion, 100/25 and 60/15 are proportional to 20/5.

Hope this helped! Good luck!