The two numbers are 10 and 7.
10+7=17 and 10-7=3
We want to find the value of the 8 in 281,480,100
Let's find the place value of each of the numbers:
2 - hundred millions
8 - ten millions
1 - millions
4 - hundred thousands
8 - ten thousands
0 - thousands
1 - hundreds
0 - tens
0 - ones
I see there are two 8's so I wouldn't be too sure of which value to find, but just in case, we have the chart made above for place values.
There is one 8 at the ten millions value.
There is one 8 at the ten thousands value.
(amount raised) = $2 × (number of classmates)