What is in_my_bag_algebraic_substitution

Objective

Substitute numbers in simple formulae

Level

5

Rules of algebra

a + b means the value of a added to the value of b

c – d means take away the value of d from the

value of c

3x means 3 times the value of x

3x = 3 × x

pq means p × q

e/m means e ÷ m

If a = 10 and b = 20 what is the value of

a + b ?

10 30 200

If c = 100 and d = 70 what is the value of

c – d ?

30 20 70

If x = 5 what is the value of

3x ?

15 35 8

If p = 2 and q = 3 what is the value of

pq ?

23 5 6

If e = 20 and m = 5 what is the value of

e/m ?

15 100 4

What’s in my bag?

a b c d e f g h i j k l m

50 48 45 42 40 36 35 32 30 28 25 1 21

n o p q r s t u v w x y z

20 18 16 15 12 10 8 7 6 5 4 3 2

Clue 1 = f + x Clue 2 = 4x

Clue 3 = k – w

36 + 4 = 40 = e 4 × 4 = 16 = p

25 – 5 = 20 = n

Unscrambling gives… pen

a b c d e f g h i j k l m

50 48 45 42 40 36 35 32 30 28 25 1 21

n o p q r s t u v w x y z

20 18 16 15 12 10 8 7 6 5 4 3 2

1) m + x n – z e + t m – y

2) a - w t – u g – w 2t 10x 4w

3) 2s n – x 2n 5s 4y v ÷ 6 5x

4) t ÷ t i + 10 s – 3 2w + 2 xy

Extension

Now make up your own clues needed to spell different

objects in your bag

Answers

1) book

2) pencil

3) planner

4) ruler

Review

Can you substitute numbers in simple formulae

a + b

c – d

4x

Level

5

© D Cavill

Valley Maths 2003

CORRECT

WELL DONE!

UNLUCKY

BETTER LUCK NEXT TIME!