!![f2升f3 maths] plz急急急急急

Sweetcream

ps*最好有埋計算過程=]THX
                        


                                           linear equations in two unknowns:


NO1]        A ship sails to and from Island A and B which are 48KM apart.The speed of the boat in still water is V KM/H and the speed of the water current is X KM/H.the upstream voyage takes 4 hours and the downstream voyage takes 3 hours.What are the values of V and X?



NO2]        The age of a boy exceeds one-third of his father's by 1.Five years later his age will be 4 less than half of his father's .What is the present age of his father?


                                  Rate and ratio:


NO1]  If ( 2x-y): (2x=y)=3:7 ,Then x:y=?


NO2]  There positive numbers are in the rato 3:4:5 .If the difference between the largest number and the smallest number is10 ,Find the numbers.


NO3]  In a certain class ,the ratio of the number of boys to the of students in the class is 5:9.If there are 16 girls, find the number of student in the class.


                                       Polygons

NO1] If the sum of the interir angles of a polygon is 4times the sum of itsexterioir angles,find the number of sides of this
Polygon.


NO2]   In a regular polygon ,each exterior angle and each interior angle are in the ratio 1:2.How many sides does the polygon
have?




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好好好好趕!!!!!!!!做左好耐都吾識~