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hint on question 13: draw a picture to verify which expressions are with the legs. they give you extra information.

So to find y, let's use 7y-4, you first add the 4 to get it away from the y. you are then left with 7y=4 after that you divide 7 from both sides leaving you with y =4/7. you find the decimal answer and that's the answer for y. just plug it in to the rest of the equations after that

It is 94.7% that uses the metric system