What is an expression called that combines numbers and operations called?

Kenzie lives 30 kilometers from her cousin houde she drives 23 kilometers before stopping for gas how many meters does she need to travel

Compare the subtraction problems 6/8 - 5/8 = 1/8 and 6/9 - 7/9 = 1/9 why is the answer to the first problem positive and the answer to the second problem negative

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