Question

1. 1/5 of a number is 20. What is the number. Please show working.
2. A boy spend 5/8 of his money and have $60. How much money did he have at first?

3. Monica spent 1 1/3 hours assembling a puzzle. How many puzzles can she assemble in 10 1/2 hours

Answer 1

1. let the number be x

1/5 of x= 20

x/5= 20

:: x= 100

2. let total money be x

spent money= 5/8of x= 5x/8

remaining money= 1-5x/8= 3x/8

according to ques

3x/8= 60

x= ₹160

3). 1 1/3 hours -- 1 puzzle
= 4/3 hours ---1 puzzle
then
1hour -- 3/4 puzzle
10 1/2 hours = 21/2 hours
21/2hours --- 3/4×21/2
= 63/8 puzzles

Answer 2

1)Let the No. be ‘x’

1/5*x=20
20*5=x
x=100
2)Let the money in starting be ‘x’
It is given the he spent 5/8 of his money and had 60$ in hand.
Therefore,60$ is (1–5/8) of his money which is 3/8.
Now,
3/8*x=60
x=(60*8)/3
x=160

Therefore, he had 160$ in the starting.
3). 1 1/3 hours means 80 mins
Now,
10 1/2 hours is 630 mins
If she takes 80 mins to solve one puzzle the the no. of puzzles she can solve in 630 mins is
630/80=7.875 puzzles
Which is 63/8 puzzles which in mixed fraction becomes 7 7/8 puzzles.
Thank you!