1. A number of two digits is less by 699 than 5 times the spuare of the number formed by reversing the digits, and the digit in the tens' place exceeds the other digit by one. Find the number. Answer: 21
2. A square floor is covered with carpet, except a border 0.5 m wide, round the carpet, which is covered with linoleum. The carpet and linoleum cost respectively $9 and $5 per m^2. The whole cost is $189. Find the length of the floor. answer: 15 m
3. The price of petrol is reduced by x per cent., and a man uses x per cent. more. as a result his petrol bill is reduced from $500 to $495. Find x. Answer: 10
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