# math

posted by .

Planets A, B and C orbit a certain star once every 3, 7, and 18 months respectively. If the three planets are now in the same straight line, what is the smallest number of months that must pass before they line up again?

• math -

hint: what is the LCM of 3,7, and 18 ?

• math -

72

• math -

72/7 = ?

Try again.

• math -

Oops I was thinking of 8 times 9
It's 126

• math -

Right.

## Similar Questions

1. ### Word problem

Plantets A, B, and C orbit a certain star once every 2, 5, and 12 months. If the three plantes are now in the same straight line, what is the smallest number of months that must pass before they line up again?
2. ### Science

Both comets and planets orbit the sun. How do their orbits differ?
3. ### Science-Help

Both comets and planets orbit the sun. How do their orbits differ?
4. ### MTH 156

If a number is increased by 37%, by what percent must it be decreased to obtain the original number?

A planet A of mass m is in a circular orbit of radius "a" around a star ( M_star >> m ). Another planet B with the same mass m is in an elliptical orbit around the same star with its length of the semi-major axis equal to "a" …
6. ### physics

A planet A of mass m is in a circular orbit of radius "a" around a star ( M_star >> m ). Another planet B with the same mass m is in an elliptical orbit around the same star with its length of the semi-major axis equal to "a" …
7. ### Physics

(II) Every few hundred years most of the planets line up on the same side of the Sun. Calculate the total force on the Earth due to Venus, Jupiter, and Saturn, assuming all four planets are in a line, Fig. 5–44. The masses are mV …
8. ### math

Planets A, B and C orbit a certain star once every 3, 7, and 18 months respectively. If the three planets are now in the same straight line, what is the smallest number of months that must pass before they line up again?
9. ### Astronomy

1. What size are most exosolar planets that have been detected?
10. ### Astronomy

Please check my answers 1. What size are most exosolar planets that have been detected?

More Similar Questions