In the xy-plane, the equations 3x + 6y = 30 and x + 2y = a/3 represent the same line for some constant a. What is the value of a?

If there are 2 hydrogens and 1 oxygen in each molecule of water, how many hydrogens are there in 89 molecules of water?

A block in the shape of a right rectangular prism has dimensions 40 cm by 35 cm by 28 cm. The block has a density of 3.2 grams per cubic centimeter. What is the mass of the block in grams?

In a random sample of 350 cars of a certain model, 8 have a manufacturing defect. At this rate, how many of 5,000 cars of this model will have a defect?

−2x + 3y = −10.5 3x + y = 5 Find the values of x and y.

z(x) = 5x − 2 h(x) = 2 − 3z(x) What is the value of h(1)?