Solution of simple linear equations

Solution of simple linear equations

Penny has a pencil case that contains a number of pencils. She has 3 other
pencils, and in total she has 13 pencils.

 

Let x be the number of pencils in the pencil case. We know that
x + 3 = 13.
This statement is called an equation.
The solution is x = 10, because 10 + 3 = 13.

David and Kirsty are twins and each has a pencil case with exactly the same number of pencils in each pencil case. They each have 2 extra pencils out of the pencil cases. They have a total of 38 pencils.

 

Let z be the number of pencils in each pencil case. We know that
2z + 4 = 38.
This is the equation that describes this relationship.
The solution is z = 17, because 2 × 17 + 4 = 38 and no other number works.

Question 1