Present age of Bob is equal to Abby's age $8\, years$ ago. Four years hence, the respective ratio between Bob's age and Abby's age will be $4: 5$ at that time. What is Bob's present age? (in $years$)
$24$
$32$
$40$
$20$
A shopkeeper sells $20$ pencils for the same amount of money as he paid for $25$ pencils. What is his gain percent?
Due to a $20 \%$ rise in price of sugar, a bachelor is able to buy $1.5\, kg$ less for $Rs.\, 135.$ What is the increased price of sugar per $kg$ in $Rs.$ ?
Sonal buys mangoes at the rate of $3 \,kgs$ for $Rs$. $21$ and sells them at $5$ $kgs$ for $Rs.$ $50 .$ To earn a profit of $Rs.\,102,$ he must sell how many mangoes in $kgs$?
Raman sells a machine for $Rs.\, 39$ lakh at a loss. Had he sold it for $Rs.\, 49$ lakh, his gain would nhave been three times the loss. What is the cost price of the machine? (in $Rs........lakh$)
By what fraction selling price $(S.P.)$ must be multiplied to get the cost price $(C.P.)$ if the loss is $20 \% ?$