Micheal used addition to find 9x100 and he said the product was 90. what did he do wrong?

I'm being volume of cylinder with 13 in. radius and 30 in height answer choices in pic

Which of these equations, when solved, gives a different value of x than the other three? a9.1 = -0.2x + 10 b10 = 9.1 + 0.2x c10 – 0.2x = 9.1 d9.1 – 10 = 0.2x

Aschool had an election where the candidates received votes in the ratio 1: 2: 3. if the winning candidate received 210 votes, how many total people voted in the election?