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How do you use the additive inverse to evaluate an expression that uses subtraction in a full sentence

Hurry if the population of of an ant hill doubles every 10 days and there are currently 100 ants living in the ant hill what will the ant population be in 20 days

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.