Addition and subtraction of fractions

A group of researchers went on an expedition to Saturn. They collected 3/5 of soil samples and then an additional 2/15. How many samples, in total, did they collect?

Calculate.

The spacecraft completed five space raids. If it used 3/16 of its fuel reserves on each raid, what fraction of fuel remains in the spacecraft?

Maxim ate 4/9 of the pizza, while Ayana ate 1/6 of the pizza. How many parts of the pizza are left?

The spacecraft delivered 6/10 of the required resources to Mercury. How many more resources does it need to deliver to complete the mission?

Calculate.

If three aliens weigh 30 kg, then how much do five aliens of the same kind weigh?

Find the least common denominator.

Calculate.

On the planet Mars, there were 9/10 crystals. Then, 1/5 of the crystals were used for the construction of a base. How many crystals are left on the planet?

A group of researchers discovered an unknown planet. If 2/3 of its surface is covered by oceans and 1/5 is covered by deserts, what fraction of the planet can be considered habitable?

Find the least common denominator.

On the planet Venus, there were 9 oceans. Then, 2/3 of the oceans dried up. How many oceans are left?

A space astronomer discovered 1/4 of the new stars in the galaxy. If there are a total of 200 billion stars in the galaxy, how many stars did he discover?

Calculate.

An alien researcher collected 4/6 samples of gas on the space station. How many more samples does he need to collect to complete the research?

In the Andromeda galaxy, there were 20 planets. An alien visited 2/5 of them. How many planets did the alien visit?

Find the least common denominator.

А spacecraft launches every 26 months. If the next launch was in May, when will the next one be?