Johnny is an engineer designing a bridge. The roadway deck for the top of the bridge needs 1600 tons of concrete to construct. The two bridge anchors need equal amounts of concrete, but only one has been built so far, using 700 tons of concrete. Johnny had to calculate how many tons of concrete the supporting pillars underneath the bridge would need, and he found that the total amount of concrete in the entire bridge will be 4800 tons. How much concrete did Johnny find he needs for the supporting pillars? Let's answer step by step:
The bridge anchors will take 700 * 2 = 1400 tons of concrete. The roadway deck and bridge anchors need 1600 + 1400 = 3000 tons of concrete. Thus, Johnny found the supporting pillars need 4800 - 3000 = 1800 tons of concrete. The answer: 1800.