Which pair of equations represents two perpendicular lines? option a: -3x +2y = 10 and 3y = 2x +12 option b: 2x + 5y = 45 and y + 2/5x = -9 option c: x= 4y +4 and x +4y=4 option d: 7x + 4y= 20 and y-3=4/7x

For the equation of the line expressed as Ax + By + C = 0, the value of the slope (m) is calculated by -A / B. For perpendicular lines, the slope of one should be the negative reciprocal of the other. From the choices given, the lines that are perpendicular is Option A. 

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.