First you determine your unknown, the amount of pounds of tomatoes. We can set that to t, for tomatoes. Next, we know each pound is .58 dollars. We know if we multiple .58 t times, or the amount of pounds we have, we'll get the total price of 2.03. So our equation is 0.58*t=2.03. Next, we isolate t to find out how many pounds were required to get the cost to 2.03. To isolate it, we do the inverse of .58*t, which is dividing, it, setting t to one. 2.03/.58=3.5 That means percy bought 3.5 pounds of tomatoes. That is reasonable, because (3*.5)+(.5*.5)=1.75, which is close to 2 dollars