If a = b, then ac = bc. this is called the
of equality. (2 words)

multiplicative property

Step-by-step explanation:

Given: 1)  2 numbers a and b.

          2) a = b

Let us consider another arbitrary number c.

Both the left and right side of the equality (2) can be multiplied by c to give:

a * c = b * c

=> ac = bc

In other words, when two equal numbers(a,b) are multiplied by the same numeric value(c) , the property of equality remains unchanged.This is also known as the multiplicative property of equality.

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