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I m trying to figure out a math question, can anyone help? If I make $30.00 every 3 weeks how long will it take to get $800.00? Thanks!? Burst pressure of 20 liter potable water bottle? Current: 1,500 watts Time: 2 hours Kilowatt-hours? How do I solve these? In calculus when integrating using u substitution how do you determine what u should be? Especially in a rations that it is not easy to tell? I can not understand expand questions of math please can you explain?