First, determine which operation to use.
The question asks "how many more boys than girls."
So, it is looking for the difference between the number of boys and the number of girls.

172 - 156 =

First, determine which operation to use.
Since there were 45 more students at this week's game, add 45 to last week's attendance.

So, 318 students were at this week's game.

First, determine what operations to use.
Since she sold 61 more snow cones on Sunday than on Saturday, add 61 to 333.

Since she sold 80 fewer snow cones on Monday than on Sunday, subtract 80.

Finally, write the expression as an equation.

333 + 61 - 80 =

First, determine what operations to use.
To find how much land is not used by the crops, subtract the amount of land both crops use from the total amount of land.

So, 378 acres of the farmer's 413 acres are not used by crops A and B.

Another way to solve this problem would be to first add 20 and 15, then subtract that total from 413.