OG详解-OG1 数学2 Q1

Choice A is correct. It’s given that Tillyearns p  dollars for every w  hours of work. This can be represented by the proportion pw​​. The amount of money, x , Tilly earns for 39w  hours of work can be found by setting up the proportion pw​​=x39​w​  This can be rewritten as 39pw = xw. Dividing both sides by w  results in x = 39p.
Choice B is incorrect. This is the amount of money Tillyearns in dollars per hour, not the amount of money Tillyearns for 39w hours of work. Choice C is incorrect. This is the amount of money Tillyearns for w hours of work plus 39, not the amount of money Tillyearns for 39w  hours of work. Choice D is incorrect. This is  the amount of money Tillyearns for w hours of work minus 39, not the amount of money Tillyearns for 39w hours of work.