If 3x+4y=7 and 2x-3y=67 then which of the following is the value of xy

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

The boiling point of water at an elevation of 0 feet is 212 degrees fahrenheit (°f). for every 1,000 feet of increase in elevation, the boiling point of water decreases by about 2°f. which of the following represents this relationship if b is the boiling point of water at an elevation of e thousand feet? a) e = 2b - 212 b) b = 2e - 212 c) e = -2b + 212 d) b = -2e + 212

X^2/100+y^2/25=1 the y-intercepts are at: a) (-10,0) and (10,0) b) (0,10) and (0,5) c) (0,-5) and (0,5)