Geometry math question no guessing and show work

You paid 28.00 for 8 gallons of gasoline. how much would you pay for 15 gallons of gasoline?

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

List x1, x2, x3, x4 where xi is the midpoint endpoint of the five equal intervals used to estimate the area under the curve of f(x) between x = 0 and x = 10.