This shows a figure containing a doing diagram. It has three rectangular boxes in the middle, the 1st containing ‘subtract 300’ linked to the 2nd box on the right containing ‘multiply by 0.4’, which is linked to the 3rd box on the right containing ‘add 20’. To the left of the 1st box is the phrase ‘number of minutes’, linked by an arrow pointing right. On the right of the 3rdrectangular box is an arrow pointing right to the number 45.

4.1 Time formula