8
Equations and Variables
We are learning to: Use a letter to represent a variable in a number sentence. Translate word problems with a variable into number sentences.
Day One Study the steps used to solve the problem in the example below.
3 bars of chocolate weigh the same as 8 packets of sweets. If each packet of sweets weighs 33 g, how much does each bar of chocolate weigh?
Circle the numbers and keywords: 3b = 8 × 33 g (‘b’ represents the bars of chocolate)
Top tip:
When we don’t know the value of a number,
we use a letter to represent the missing number.
Link with operation needed (+, −, × or ÷): Multiply (×). Divide (÷). Use a strategy: Visualise.
Estimate and calculate: 3b = 264 g
b = 88 g Answer: 88 g
Summarise and check how you got your answer: Each chocolate bar weighed 88 g. I multiplied 8 × 33 g to find the total weight of 8 packets of sweets. I then divided that number by 3 to find the weight of each bar of chocolate.
Try these. 1
At Calypso’s Crazy Circus, 6 children’s tickets cost the same amount as 4 adults’ tickets. If each child’s ticket costs €5, how much does an adult’s ticket cost?
2
Answer:
Marks:
/2
16 unicycles weigh the same as 9 tandem bicycles. If a tandem bicycle weighs 32 kg, what is the weight of 1 unicycle?
Answer: 3 Aoife spent 3
Marks: 5 of her weekly pocket money buying a clown costume. If she
spent €15 on the costume, how much pocket money does she get per week? (Hint: We know that Aoife only spent part of her pocket money. This means that your answer must be greater than €15.)
/2
Answer: 36 Strand: Algebra Strand Unit: Equations and Variables
Marks: Today’s Marks:
/2 /6
Week 8
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