If 2(x + 5) – (3x – 4) = 12, what is the value of x?

Me because some of question i don’t understand

An initial investment of $100 is now valued at $150. the annual interest rate is 5%, compounded continuously. the equation 100e0.05t = 150 represents the situation, where t is the number of years the money has been invested. about how long has the money been invested? use your calculator and round to the nearest whole number. years

What number is 7 units left of -15?