Helppp help meh

a) none of the above

b) the second one and the fourth one

Step-by-step explanation:

Use the process of elimination throughout

a) since it's an expression, the book example doesn't work out very well.

The first one means that x has to equal 5 but in reality, x can equal anything.

The second one requires addition between 4 and x, but the expression has multiplication.

The third one requires subtraction instead of multiplication.

The fourth one doesn't add up. How can they read 20 pages of a book with just 4 pages?

b) Since it'a an equation, this scenario works fairly well.

The first one requires multiplication, not addition.

The third one requires subtraction, not addition.

However, the second one works because you can work x out (14) since 21 is the total number of dogs.

The fourth one also works because bringing in 7 dogs means addition, which is what is used in the equation.