I helped 3.6 customer per half hour yesterday. so i helped _____ customers in 7.5 hour yesterday

We can summarize that

By applying the law of cosines: 

c² = a² + b² - 2abcos(C) 

where: 

a,b, and c represent the triangle's sides and C denotes the angle opposing side c.

Let us assign:

a=170 miles

b=200 miles

c=160 miles

Thus, we establish: 

160² = 170² + 200² - 2(170)(200)cos(C).

We now aim to solve for C.

25,600 = 28,900 + 40,000 - 68,000cos(C).

25,600 - 28,900 - 40,000 = -68,000cos(C).

-43,300=-68,000cos(C).

Thus, cos(C)=0.6367.

C=arc cos(0.6367)--------> C=50.45°.

Consequently, the captain should adjust toward island B by

180 - 50.45 = 129.55 degrees.

The final answer is

129.55 degrees

Neither individual's solution is accurate.

Annabelle also made an error; although multiplication was involved, the numbers were split incorrectly, giving her "46710."

The correct outcome should be 18,690,300