Explain how knowing how to find the least common multiple of two numbers can help you solve the system of equations presented here by eliminating the x-terms

If a baby uses 15 diapers in 2 days how many diapers will the baby use in a year

How to solve a simultaneous equation involved with fractions?

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.