How do you estimate the sum or difference of 5/12 + 7/8

Twenty-five percent of the customers entering a grocery store between 5 p.m. and 7 p.m. use an express checkout. consider five randomly selected customers, and let x denote the number among the five who use the express checkout.

How to solve a simultaneous equation involved with fractions?

What is the volume of a cone with a height of 6 cm in the radius of 2 cm