Solve the Equation: Finding the Missing Number in 12+?+3-1=29

Question

$12+?+3-1=29$

00:00 Identify the missing number

00:04 Given that all operations are addition/subtraction

00:07 We may use the commutative property and solve in a different order

00:18 Arrange the exercise in the simplest way possible

00:27 Continue to solve

00:36 Isolate our unknown

00:49 And this is the solution to the question

To find out which number is missing, we solve the entire exercise to know which number we will have to add to obtain a result of 29:

$12+3-1=$

$15-1=14$

To make 14 equal to 29, we will have to add 15.

Let's verify:

$29-14=15$

$15$