Answer: 80 miles
Step-by-step explanation:
First we need to isolate the variable so we add 15 to both sides which is
w/4=43 then we need to multiply by 4 to both sides so its 4w=172
then divide by 4 which is 43 so the answer is w=43
You can use the sum and difference identities which for cosine is cos(a+b)= cosacosb-sinasinb