If a= -4.2 what is value of -a

Jackie purchased 3 bottles of water and 2 cups of coffee for a family for $7.35. brian bought 4 bottles of water and 1 cup of coffee for his family for $7.15. how much does each bottle of water cost? how much does each cup of coffee cost? i need this done

What is the x-intercept and y-intercept of the equation 2x+1. 2o

Find the nonpermissible replacement for binthis expression.b2/5b +5