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1 4. A boat, rowing in favour of current, goes 15 km per hour and rowing against the

current goes 5 km per hour. Find the speed of the boat and current.

15. A labourer of a garments serves on the basis of monthly salary. At the end o f

every year she gets a fixed increment. Her monthly salary beomes Tk. 45 00

after 4 years and Tk. 5 000 after 8 years. Find the salary at the beginning of he r

service and amount of annual increment of salary.

16. A system of simple equations are xy 10
    3 x 2 y 0

a. Show that the equations are consistent. How many solutions do they have?

b. Solving the system of equations, find (x,y).

c. Find the area of the triangle formed by the straight lines indicated by the

equations with thex-axis.

17. If 7 is added to the num. of a fraction, the value of the fraction is the integer 2. Again ,

if 2 is subtracted from the denominator, value of the fraction is the integer 1.

a. Form a system of equations by the fraction

y

x

.

b. Find (x,y) by solving the system of equations by the method of cross-

multiplication. What is the fraction?

c. Draw the graphs of the system of equations and verify the correctness of the

obtained values of (x,y).