The construction site needs to use raw materials with a length of 7.4 meters to make 100 sets of steel bars, each set of 3 bars, and the lengths are 2.9 meters, 1.5 meters, and 2.1 meters. I would like to ask: How many raw materials should be used at least?
工地要用每根长7.4米的原材料做100套钢筋，每套3根，长度分别为2.9米、1.5米、2.1米．请问：至少要用多少根原材料？
<result>90</result>