Well 62% in decimal format is 0.62 but if you want to find the temperature at night you can multiply 130 by 0.38 which is 38%
Yes, yes it is; well done.
Answer:
Sister = 15 years old
Brother = 12 years old
Step-by-step explanation:
Right now, if the brother is B years old and the sister is S years old, B = (4/5)S because the ratio from brother to sister is 4:5, so if one unit is X, B = 4X and S = 5X
Three years ago, the brother was B-3 years old and the sister was S-3 years old. Keeping one unit as X, we have
B = 3X
S = 4X
B-3 = (3/4)(S-3)
Therefore, we have a system of equations
B = (4/5)S
B-3 = (3/4)(S-3)
Substitute (4/5)S for B into the second equation to only have one variable
(4/5)S - 3 = (3/4)(S-3)
(4/5)S - 3 = (3/4)S - 9/4
add 3 to both sides and subtract (3/4)S from both sides to isolate the variable and its coefficient
(1/20)S = 3/4
multiply both sides by 20 to isolate the S
S = 15
B = (4/5)S = 12
Answer: a) 15 b)
Step-by-step explanation:
Let X be the number of days:
a)
For LESSONS:
Jordan does 10 / day ( 10*X)
Marco 5 / day ( 5*X)
Junyi 5 / day ( 5*X)
For TESTS:
Jordan does 5 / day ( 5*X)
Marco 10 / day ( 10*X)
Junyi 8 / day ( 8*X)
for each they need a total of 300
a) 
days for the lessons
b) 
days for the tests
so they need 15 days to finish both tasks
now if Junyi gets sick we just eliminate his contribution
a) 
days for the lessons
b) 
days for the tests
so in 20 days they will finish without him
If jordan works 10 hours a day, we just replace him with 10/24
a) 
days for the lessons
b) 
days for the tests
so at the end to complete both tasks they need 29.58 days
