A line has a slope of One-fourth and passes through point (0.4, negative one-half). What is the value of the y-intercept?

Look at attachment. has all info needed. need

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18