1. If (x+yi) = 7 + 9i Where x and y are real, what is the value of (x + yi)(x-yi)? 2. When you started your homework assignment, your friend already had 6 exercises done. You can do about 3 exercises per minute, whereas your friend can only do 2 exercises per minute. How many minutes will it take you to catch up to your friend. 3. A man is 35 years old, and his son is 7 years old. In how many years will the father be 3 times as old as his son will be then? 4. Find two consecutive positive integers such that the difference of their squares is 37 5. Richard's present age is 12 years older than Rita's present age. Ten years ago Richard's age was three times Rita's age. Find the present ages of Richard and Rita. 6. Solve for x if x+6=x 7. Find the value a-[4b-(2c+1)]; where a -8; b=-7 and c = 14. 8. In a class of 35 pupils, 20 play Table-tennis, 10 play handball and 5 play both games. a. How many pupils play at least one of the games? b. How many pupils play neither of the games? c. How many pupils play only table-tennis? 9. Solve for y it y-3-y=-3 10. Solve the equation 3 8-21