1,200 টাকা
Let. Tk. x is the additional money Mrs. Barbara invests at 8% interest
Her total investment = (x$\times$2,400) tk
According to the question.
(2,400 x 5%) + (x$\times$8%) = (2,400 + x) x 6%
=> 120+$\frac{8x}{100}$ = (2,400+x)x$\frac{6}{100}$
=> 120+$\frac{8x}{100}$ = 144+$\frac{6x}{100}$
=> $\frac{8x}{100}$-$\frac{6x}{100}$ = 144-120
=> $\frac{2x}{100}$ =24
=> $\frac{x}{50}$ = 24
so, x=1,200 টাকা
Total annual sales is Tk. 6.80.000.
Salesman’s annual salary = 15,000 x 12 = 1,80,000 tk
Amount of commission = 2,65,000 – 1,80,000 = 85,000 Tk.
Now, he cams 12.5 tk as commission when his sales = 100 tk
so, earns 85,000 tk, as commission when his sales = $\frac{100\times 85000}{12.5}$= 6.80000 tk
1,600
Let the width of the rectangular field be x meter
Length of the rectangular field is 3x meter
According to the question, 3x$\times$x= 768
=> 3x$^{2}$ = 768
=> x$^{2}$ = $\frac{768}{3}$
=> x$^{2}$ = 256
so, x=16
so, length= 3 X 16 = 48 meter and width = 16 meter
so, Perimeter = 2(48 + 16) = 128 meter
Perimeter of square = Perimeter of rectangular field
so, Perimeter of square = 128 meter
so, Side of square = $\frac{128}{4}$ = 32 meter = 32 X 100 = 3200cm
so, Area of square field = (3200 x 3200) sq.cm.
Area of tiles = (80 X 80) sq.cm.
so, Number of Required tiles = $\frac{3200×3200}{80×80}$ =1,600
x= $\frac{3}{5}$
$\frac{4}{2x+1}+\frac{9}{3x+2}$ = $\frac{25}{5x+4}$
=> $\frac{4}{2x+1}+\frac{9}{3x+2}$ =$\frac{15}{5x+4}+\frac{10}{5x+4}$
=> $\frac{4}{2x+1}-\frac{10}{5x+4}$ = $\frac{15}{5x+4}+\frac{9}{3x+2}$
=> $\frac{20x+16-20x-10}{(2x+1)(5x+4)}=\frac{45x+30-45x-36}{(5x+4)(3x+2)}$
=> $\frac{6}{(2x+1)(5x+4)}=\frac{-6}{(5x+4)(3x+2)}$
=> $\frac{1}{2x+1}=\frac{-1}{3x+2}$
=> 3x+2=-2x-1
=> 3x+2x = -1-2
=> 5x =-3
so, x= $\frac{3}{5}$
