1. If a varies directly with the square of b, and b in turn varies inversely with d, if a is 90 when d is 5: a. write the variation equation

b. find a when d is 9.

2. Find the equation of the line that passes through (3.8, -1.2), (2.2, 3.1).

3. The standard fare for a taxi in one city is $5.50, plus $0.30 per mile. Write the linear equation that describes the cost of a cab ride in terms of the length of the ride in miles. Then use your equation to find the cost of a 6-mile ride, 8.5 mile ride and 12-mile ride.