Yup, the amount of 0's is the exponent. for example 1000= 10^3, hope this helped :)
Because in an equilateral triangle all angles should measure 60 degrees otherwise all sides would not be equal.
After one week, Jacob has earned $80 from babysitting, so his change is an increase of $80. The next week, he spends $85, so he experiences a decrease of $85. Over the two weeks, his overall change is $80-$85=-$5, or a decrease of $5.