This question asks how students can formulate linear equations from worded questions.

The first step is to give each person an algabraic symbol. j for John, s for Sandra and k for Kathy works fine.

Next, students shoud identify key words in the question that translate in to mathematical symbols. In this case, 'has' means '=', 'more than' means '+' and 'times as many as' means 'x'.

Students should create 3 equations. The first should be J = 12. The next is S = 10 + K. The next is K = 4 x J.

Students should then subsititue J in to K = 4 x J and then substitute that answer in to S = 10 + K in order to find S.

The final answer should be 58 marbles.

((2x + 3)/(x-4)) - ((2x-8)/(2x+1)) = 1

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John has 12 marbles. Sandra has 10 more marbles than Kathy. Kathy has 4 times as many marbles as John. How many marbles does Sandra have?