How do you solve for a negative exponent? if i had 5 to the power of negative 2, how would i solve it?

Evaluate 4 a for a = 5 2/3 . express your answer in simplest form.

Marlow is comparing the prices of two trucks rental compaines company a charges $3 per hour and an addtional $75 as serivce charges company b charges $2 per hour and an additional $85 as serivce charges

Tim's phone service charges $23.06 plus an additional $0.22 for each text message sent per month. if tim's phone bill was $28.56, which equation could be used to find how many text messages, x, tim sent last month?