Answer :
First you'll need to get the same denominator. So instead of 3/5 and 3/8 you'll have 24/40 and 15/40. Now that we've changed the value of the denominator, the 40/40 will now represents the 1 hour that Jenny has before bedtime. So you add 24/40 and 15/40 and get 39/40. 39/40 stands for the time that Jenny has already spent brushing her teeth and texting her friend all together. Since the 1 hour is 40/40 subtract 39/40 from it to get 1/40. 1/40 is equal to the rest of the time Jenny spends reading or 1.5 minutes.
15 minutes
Further explanation
Given:
- Jenny has an hour before its bedtime.
- Jenny spends [tex]\frac{3}{5}[/tex] of an hour texting a friend and [tex]\frac{3}{8}[/tex] of the remaining time brushing her teeth and putting on her pajamas.
- She spends the rest of the time reading her book.
Question:
How long did Jenny read?
The Process:
Step-1: We need to calculate the time of texting a friend in minutes.
Recall that [tex]\boxed{1 \ hour = 60 \ minutes}[/tex]
[tex]\boxed{\frac{3}{5} \ hour = \ ? \ minutes}[/tex]
[tex]\boxed{\frac{3}{5} \ hour = \frac{3}{5} \times 60 \ minutes}[/tex]
We crossed out 5 and 60, i.e., [tex]\boxed{60 \div 5 = 12}[/tex]
[tex]\boxed{\frac{3}{5} \ hour = 3 \times 12 \ minutes}[/tex]
Therefore,
[tex]\boxed{\boxed{ \ \frac{3}{5} \ hour = 36 \ minutes \ }}[/tex]
Step-2: Let us calculate the remaining time.
[tex]\boxed{60 \ minutes - 36 \ minutes = 24 \ minutes }[/tex]
Step-3: Jenny spends [tex]\frac{3}{8}[/tex] of the remaining time brushing her teeth and putting on her pajamas.
[tex]\boxed{\frac{3}{8} \times 24 \ minutes}[/tex]
We crossed out 8 and 24, i.e., [tex]\boxed{24 \div 8 = 3}[/tex]
[tex]\boxed{= 3 \times 3 \ minutes}[/tex]
[tex]\boxed{\boxed{ \ 9 \ minutes \ }}[/tex]
Step-4: Let us calculate how long Jenny read for the rest of time.
[tex]\boxed{24 \ minutes - 9 \ minutes = 15 \ minutes }[/tex]
Thus, Jenny spent 15 minutes reading a book before its bedtime.
- - - - - - - - - -
Quick Steps:
Let us calculate how long Jenny read for the rest of time.
[tex]\boxed{ \ = \bigg(1 - \frac{3}{8} \bigg) \times \bigg(1 - \frac{3}{5} \bigg) \times 60 \ minutes \ }[/tex]
[tex]\boxed{ \ = \frac{5}{8} \times \frac{2}{5} \times 60 \ minutes \ }[/tex]
[tex]\boxed{ \ = \frac{10}{40} \times 60 \ minutes \ }[/tex]
[tex]\boxed{ \ = \frac{1}{4} \times 60 \ minutes \ }[/tex]
[tex]\boxed{\boxed{ \ 15 \ minutes \ }}[/tex]
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Keywords: Jenny, has an hour, before its bedtime, spends 3/5 of an hour, texting a friend, 3/8 of the remaining time, brushing her teeth, putting on her pajamas, reading her book
