What is bigger 1.40 or 1.42

Ageologist had two rocks on a scale that weighed 4.6 kilograms together.rock a was 0.5 of the total weight.how much did rock a weigh?

Which shows the correct substitution of the values a,b and c from the equation 1=-2x+3x^2+1

Aconstruction worker has rope 9 m long he needs to cut it in pieces that are each 3 /5 m long how many such pieces can he cut without having any rope leftover?