PUZZLED HELP! If I solve an equation, get the answer, but when I do a" check step", does it mean that I have to solve the equation again? Example: 3(x – 1) + 2x = 6x is equaled to -3, but when I checked it the answer was false...-16=-18 (false)

Alake near the arctic circle is covered by a 222-meter-thick sheet of ice during the cold winter months. when spring arrives, the warm air gradually melts the ice, causing its thickness to decrease at a constant rate. after 333 weeks, the sheet is only 1.251.251, point, 25 meters thick. let s(t)s(t)s, left parenthesis, t, right parenthesis denote the ice sheet's thickness sss (measured in meters) as a function of time ttt (measured in weeks).

Due to bad planning, two of the local schools have their annual plays on the same weekend. while 457 people attend one, and 372 attend the other, only 104 people were able to attend both. how many people went to at least one play?

Can someone me with this? i’m not sure what to put for my equations.