What value of x will make the equation below true? −x=4

The ph level of a blueberry is 3.1 what is the hydrogen-ion concentration [h+] for the blueberry

I’m still confused on how to work the percentages

Jack is considering a list of features and fees for current bank: jack plans on using network atms about 4 times per month. what would be jack’s total estimated annual fees for a checking account with direct paycheck deposit, one overdraft per year, and no 2nd copies of statements? a. $44 b. $104 c. $144 d. $176