3+4 = 7
so
21 / 7 3
3 x 3 = 9
3 x 4 = 12
answer
£21 in ratio 3:4 is £9:£12
Since sum indicates addition, you want to add the two terms together.
B + (5x2)
If the answer needs to be simplified, you can do the multiplication to get:
B + 10
Answer:

Step-by-step explanation:
<u>Recall:</u>
- Sinusoidal Function ->

- Amplitude ->

- Period ->

- Phase Shift ->

- Vertical Shift/Midline ->

<u>Given:</u>
- Amplitude ->

- Period ->

- Phase Shift ->

- Vertical Shift/Midline ->

<u>Conclusion:</u>
The equation that models the situation is 
Hope this helped! I've attached a graph of the function so you can understand it better!