Block 8 - Substitution

• Substitution

  A) 81+42-4

  B) 123-4

  C) 119

  D) 20+20-7

  E) 33

  F) 21+24+8

  G) 53

  H) 27+27+9

  I) 63

  
• Substitution

  The cost of hiring a car (C) is a £45 fixed price plus £60 per day

  1. Write a formula for the cost of hiring the car

  C = 45 + 60d

  
  

  2. how much will it cost to hire the car for 4 days?

  C = 45 + 60 x 4 = £285
• Substitution

  The total cost (P) of buying (d) dollars if the exchange rate is $1 = £0.64 and there is a fixed commission fee of £12

  1. write a formula for the cost of buying dollars

  P = 0.64d + 12

  2. Work out the total cost of buying $200

  P = 0.64 x 200 + 12

  P = 140

  3. How many dollar would you get from £500?

  500 = 0.64d + 12

  488 = 0.64d

  d = $762.50
• Substitution

  A) 100/4

  B) 25