The HCF of two numbers is 21 and their LCM is 840. If one of the numbers is 49, then the other number is:

A boat moves 25km upstream and 39km downstream in 8 hours. It travels 35km upstream and 52km downstream in 11 hours. What is the speed of the stream if it travels at a uniform speed?

A car runs first 275 km at an average speed of 50 km/h and the next 315 km at an average speed of 70 km/h. What is the average speed (in km/h) for the entire journey?

Find the greatest number which divides 108, 124 and 156, leaving the same remainder. 

How many numbers are there from 500 to 650 (including both) which are neither divisible by 3 nor by 7?

The length and the breadth of a rectangle are made to increase and decrease, respectively, by 8% and 10%. What is the percentage increase or decrease in its area?

A sum invested at compound inrerest amounts to ₹7,800 in 3 years and ₹11,232 in 5 years. What is the rate per cent? 

An item costs ₹400. During a festival sale, a company offers a sale discount that offers x% off on its regular price along with a discount coupon of 10%. The price of the item after using both the sale discount and the discount coupon, is ₹216. What is the value of x?