A 5-inch candle burns down in 4 hours. How far has it burned after 7 1/2 hours?

9 3/8 inches

Step-by-step explanation:

Inches of candle : hours it burned

= 5 inches : 4 hours

How far has it burned after 7 1/2 hours?

Let

x = how far it has burned (inches)

Inches of candle : hours it burned = x inches : 7 1/2 hours

Equate both ratios

5 inches : 4 hours = x inches : 7 1/2 hours

5/4 = x ÷ 7 1/2

5/4 = x ÷ 15/2

5/4 = x * 2/15

5/4 = 2x/15

Cross product

5 * 15 = 4 * 2x

75 = 8x

x = 75/8

x = 9 3/8 inches

x = how far it has burned (inches) = 9 3/8 inches

5x+40

5(x + 8)

7x - 49

7(x - 7)

18x + 9

9(2x + 1)

15x - 10

5(3x - 2)

step-by-step explanation:

for number one all you have to do is factor 5 out of 5x + 40

for number 2 factor 7 out of 7x - 49

for number three factor 9 out of 18x + 9

for number four factor 5 out of 15x - 10