Answer:
23% of Michael's rock collection is metamorphic rock.
Step-by-step explanation:
We are given the following in the question:
Percentage of igneous rock in the collection = 27%
Percentage of sedimentary rock in the collection = 50%
Remaining rocks are metamorphic rock.
Total collection = 100%
Percentage of metamorphic rocks =

Thus, 23% of Michael's rock collection is metamorphic rock.
The Area of the trapezoid is 88 not 91
From the given problem, it says show how to make a ten to solve 13-7.
Subtracting 13 to 7 gets 6. In order to get a 10, subtract 10 by 6. 10-6 = 4.
So, you need to add 4 in order to make a ten.
Disclaimer: What do you by make a ten to solve 13-7?