Ican't figure this out can someone answer and list steps

Keisha makes a large sandwich for a family picnic she takes 1/2 of them the sandwich to the picnic her family eats 3/8 of the whole sandwich what fraction of the whole sandwich does keisha bring back from the picnic

Write the fraction 9/50 as a decimal if needed round to the nearest hundredth

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?