a. Suppose that a firm that makes bicycles buys its tires, in pairs, and frames from other firms, and that they count as (the only two, assume) inputs for the bicycle firm. What do the isoquants for bicycles look like?

b. If a utility can burn either of its two possible fuels, oil or natural gas, with fixed prices and in any combination, to power its turbines, what do its isoquants for producing electricity look like?