Ineed , i have a test tomorrow and i don't know how to dome! : ,(

3.5×10^8 is the answer

Just remember to do PEMDAS
P,parentheses do what's in them first
E, exponent do what's in them 2nd. for M & D you just do multiply or divide whatever one comes 1st
for A & S then add and subtract you don't have
to do add at first it's just what come first.
hoped that helped

Jsnsndndnfjndndndndnd