Caleb took 18 photos at the zoo. one sixth of his photos are of giraffes. how many of calebs photos are giraffes

Pls , the question is in the picture!

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?

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.