How do you go from 98 to 720 using just one letter?

How many triangles are there on the puzzle below?

If 21x = 79x, what is the value of x?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

There is a box. The area of its top is 240 square units, the area of the front is 300 square units and the area of the end is 180 square units.

Can you calculate the dimensions of this box with the given data?

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

Can you find out the remainder when 3^300 is divided by 5?

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?