The ratio of the total surface areas of two similar prisms is 49 : 64. What is the ratio of their sides?

Step-by-step explanation:

Area is a squared measure whereas perimeter is a one-to-one measure.  Perimeter measure is also the same thing as "the ratio of the sides".  So get from the ratio of the sides to the ratio of the area, you square the one-to-one, since area is a squared measure.  You do the same to go backwards from area to one-to-one (take the square root).  

Since we are given the ratio of the areas, those numbers are the one-to-one measures squared.  Take the square root of each to find the one-to-one:

7:8 is the ratio of the sides.

what

all three statements are true

step-by-step explanation:

a shipping fee of 5% is charged online with every item purchased online

first let's just take each option and calculate them based on this, to see if the answers matched

keith buys a 40 dollar book

40 x 0.05 = 2

therefore there will be a two dollar fee on keith's book

40 + 2 =42

the first statement is true

a chair costs $80

80 x 0.05 = 4

80 + 4 = 84

the second statement is true

george buys a 20 dollar calculator

20 x 0.05 = 1

20 + 1 = 21

the third statements are true

all three statements are true