Total amount of time that Joe has before going to soccer practice is 45 minutes. He spent 20 minutes eating a snack. This means that amount of time left after eating the snack is total amount of time that he has - the amount of time he spent on eating the snack. This becomes
45 - 20 = 25 minutes
He spent the rest of the time doing Homework. This means that he spent 25 minutes doing homework.
The equation to express how long Joe spent doing homework will be
Let x = amount of time spent doing home
x = total amount of time he had - amount of time he spent eating snack
