I need help with this question... major grade test.

Aline has a slope of 1/4 and passes through point (0.4,-1/2). what is the value of the y-intercept?

Cassie is traveling 675 miles today to visit her brother and his family. so far, she has stopped for gas three times. at the first stop, she put in 7.1 gallons of gas and paid $23.79. at her second stop, she put in 5.8 gallons of gas and paid $19.08. and, at the third stop, 6.6 gallons and paid $20.39. at which stop did casey pay the most for gas?

According to the data set, where should the upper quartile line of the box plot be placed?