1.Ben has four more than twice as many CDs as Jack .If they have a total of 31 CDs ,how many CDs does Jack have
2.Jack wants to replace the flooring in his rectangular Kitchen .He calculates the area of the floor to be 12.8 square meters ,The actual area of the floor is 13.5 square meters .What is the relative error in calculating the area of the floor ,to the nearest thousandth?
3.A right triangle contains a 38° angle whose adjacent side measures 10 centimeters.What is the length of the hypotenuse ,to the nearest hundredth of a centimeter
4.On the set of axes below ,graph and label the equations y=|x| and y=3|x| for the interval -3小等于x小等于3.）
5.On the set of axes below ,solve the following system of equations graphically and state the coordinates of all points in the solution set .y=-x²+6x-3 x+y=7.(要圖）