if 213=25,214=36,215=47,216=58 then 218=?

Question

Nothng more. Acc to me ans should be 91 bt my frnd told that it is 811. How?

Answer 1

A linear pattern emerges. The difference between the smaller numbers is 11, while the difference between the larger numbers is 1. This can be written as an equation y-213=(x-25)/11.

When x=25, y=213; x=36, y=214; x=47, y=215; x=58, y=216.

When y=218, 55=x-25, so x=80.