In a business, A invested 1200 rs. more than B. B invested his amount for 15 months while A invested for 4 months more than that of B. If total profit was 1240 rs. in which the profit of B is 280 Rs. less than that if A. then what was the invested amount of A?

Ans. 
Let B’s investment = x rs.
∴ A’s investment =( x + 1200) rs.
Ratio of the profits of A and B = (x+1200)*(15+4):x*15 = {19(x+1200)}:15x
Now,let the total profit of A =y
∴ total profit of B = (y-280)
But total profit = 1240
⇒y+(y-280)=1240
⇒2y=1520
⇒y= 760
∴profit of A = 760rs.
Profit of B = 760-280=480 rs.
Ratio of profits= 760:480 = 19:12
According to the question,

19(x+1200)/15x = 19/12

12x+14400 = 15x

⇒3x = 14400
⇒x = 4800 rs.
⇒investment of A = 4800+1200
                          = 6000 rs.