We can use the is/of = p/100 method here. Our given values are 90% and 1000. Think: "What number is 90% of 1000?" Let's plug in our values.
x/1000 = 90/100
Solve for x.
x = (1000)(0.9)
x = 900
So, 900 is 90% of 1000.
Well you find how much the error was and divide it by the amount he predicted.
30/230= 0.13 0.13=13%
Answer:

Step-by-step explanation:
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She bought 6 books in all because if you divide the whole number of all the books in all which is $32 divide that by 4 so..
32 ÷4=8
so thats just the 4 books then she buys 16 more dollars worth that which you then multiply 4 times 8 which give you 16 so you then add the 4 books to the other 2 books spent on the next day
ANSWER: 6 BOOKS IN ALL