The result of subtracting one number from another number is known as the difference.

The value used to subtract from the whole is known as the subtrahend.

Explain how to balance an equation with two unknowns

Maths

In this unit pupils will compare and represent the structure of problems with two unknowns using a bar model. They will systematically solve problems with two unknowns using trial and improvement. In the future unit this understanding is formalised through the use of algebraic notation. 

In the prior unit pupils explained how to balance equations with addition or subtraction expressions and used knowledge of balancing equations to solve problems. In this unit pupils will compare and represent the structure of problems with two unknowns using a bar model. They will systematically solve problems with two unknowns using trial and improvement.

Solving problems with two unknowns

In this problem, the difference between the known addends is 20  Match the expressions correctly.  

If we call the first missing addend a, match the expressions correctly.

If we call the first missing addend a, what is the second addend when a = 10? {{ }}

Match the value of the first missing number with the correct value of the second missing number.

Match the value of the second missing number with the correct value of the first missing number.

If the value of the first missing number is a, what is the value of the second missing number when a = 68? 

Match the pairs of missing unknown numbers to find possible solutions. 

If one of the unknowns is 60, what would the other unknown be?

Laura has some triangles and squares. She chooses some of the shapes and when she counts the number of sides, she finds that the total is 48 
How many of each shape could she have?

Laura has some squares and pentagons. She chooses some of the shapes and when she counts the number of sides, she finds that the total is 48 
How many of each shape could she have?

I use two different lengths of wood to make a fence 7 m long. One length of wood is 70 cm and the other is 105 cm. 
If two 105 cm planks were used, how many of length 70 cm were used? {{ }} planks

Jun spends 8 hours in maths and science lessons. A maths lesson is 55 minutes,a science lesson is 65 minutes. Jun had the same number of maths and science lessons. How many of each lesson did he have?

Starter Quiz