According to the school survey, 12% of the students at rockwood junior high school speak spanish. there are 36 students at the school who speak spanish. how many students were surveyed?

The length of a rectangle plus its width is 25 cm. the area is 156 square cm. what are the length and width of the rectangle? separate the answers with a comma.

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.