The coordinates of the vertices of triangles are listed in the options below. which is a right triangle?

d(−2, −3), e(−5, −7), f(6, −7)
a(−3, 2), b(−4, −9), c(8, 1)
p(−6, 2), q(1, 0), r(−3, −2)
x(3, 1), y(−4, −3), z(−8, 3)

How many liters of peroxide should be added to 12 liters of an 8% peroxide solution so that the resulting solution contains 16% peroxide?   original added new amount of peroxide 0.96 liters x 0.96 + x amount of solution 12 liters x 12 + x 0.18 liter 1.14 liters 1.92 liters 2.10 liters