Answer:

Step-by-step explanation:
we know that

Remember the identity

step 1
Find the value of 
we have that
The angle alpha lie on the III Quadrant
so
The values of sine and cosine are negative

Find the value of sine

substitute




step 2
Find the value of 
we have that
The angle beta lie on the IV Quadrant
so
The value of the cosine is positive and the value of the sine is negative

Find the value of cosine

substitute




step 3
Find cos (α + β)

we have




substitute



Yes you did do this correctly
Answer:
19
Step-by-step explanation:
The boots are the value of 10, since 3 equal 30. The man is the value of 5 since there are two men (10) and one boot (also 10) which made 20. The ribbon is the value of 4 since there is one man (5) and 2 ribbons (8 ) which made 13. add 10, 5 and 4 and you get 19.