Let the unit digit is b and tenth dight is a So the number = 10a + b
According to first condition, a + b = 16 ........(i)
According to second condition,
10a + b + 18 = 10b + a
= 10b + a - 10a - b = 18
= 9b - 9a = 18
= b - a = 2 ........ (ii)
By adding equation (i) and (ii),
a + b + b - a = 16 + 2
= 2b = 18
= b = 9
From equation (i),
a + b = 16
= a + 9 = 16
= a = 7
The original number
= 10a + b
= + 9
= 79 (Answer)
Dolar can do a piece of work in 4 hours; Zoha and Khadem together can do it in 3 hours, while Dolar and Khadem together can do it in 2 hours. How long will Zoha alone take to do it?
Dolar's 1 hour's work =
(Zoha & Khadem)'s 1 hour's work =
(Dolar & Khadem)'s 1 hour's work =
(Dolar, Zoha & Khadem)'s 1 hour's work
Zoha's 1 hour's work = =
Time taken by Zoha to complete the work 12 hours
Let cost price of the product is x ATQ,
= 1920 - x = x - 1280
= 2x = 3200
= x = 1600
At 25% the selling price
= 2000 Tk