Answer:
They raised $150
Explanation:
In order to solve this you just need to reverse the actions that they took in order to get to 47 dollars left, so the total amount they raised will be represented by letter X, so 47 is what is left after spending 29 on trash bags and 74 on waterproof boots, that means that from the total we are withdrawing those amounts and the result will be 47:
Total-Money spent=47
X-29 - 74= 47
x=47+74+29
x=150
So now we know that they originally had 150 dollars and that would be what they raised.