#!/usr/bin/env ruby
# -*- coding: utf-8 -*-


puts"1.6x+3x=?"
puts"2.21y➗3y=?"
puts"3.23b-43b=?"
puts"4.45n×3n=?"
puts"x= -12 、y= 4のとき、4xー8yはいくつになるでしょう?"

while true
  while true
  puts"1の答えを入力:"
  kaitou = gets.chomp.to_i
  if kaitou == "9x"
    puts"正解!"
  else
     puts"不正解...."
      redo
    end
  end

    while true
    puts"2の答えを入力:"
    kaitou = gets.chomp.to_i
    if kaitou == "7y"
    puts"正解!"
    else
      puts"不正解...."
      redo
     end
    end

while true
  puts"3の答えを入力:"
  kaitou = gets.chomp.to_i
  if kaitou == "-20b"
    puts"正解!"
  else
    puts"不正解...."
    redo
  end
end

while true
  puts"4の答えを入力:"
  kaitou = gets.chomp.to_i
  if kaitou == "135x"
    puts"正解!"
  else
    puts"不正解...."
    redo
  end
end
end